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• fill an array with Int like a Char; C++, cin object

  - by Duknov007

  This is a pretty simple question; first time poster and long time looker. Here is my binary to decimal converter I wrote: #include <iostream> #include <cmath> using namespace std; const int MAX = 6; int conv(int z[MAX], int l[6], int MAX); int main() { int zelda[MAX]; const int d = 6; int link[d]; cout << "Enter a binary number: \n"; int i = 0; while (i < MAX && (cin >> zelda[i]).get()) //input loop { ++i; } cout << conv(zelda, link, MAX); cin.get(); return 0; } int conv(int zelda[MAX], int link[6], int MAX) { int sum = 0; for (int t = 0; t < MAX; t++) { long int h, i; for (int h = 5, i = 0; h >= 0; --h, ++i) if (zelda[t] == 1) link[h] = pow(2.0, i); else link[h] = 0; sum += link[t]; } return sum; } With the way the input loop is being handled, I have to press enter after each input of a number. I haven't added any error correction yet either (and some of my variables are vague), but would like to enter a binary say 111111 instead of 1 enter, 1 enter, 1 enter, etc to fill the array. I am open to any technique and other suggestions. Maybe input it as a string and convert it to an int? I will keep researching. Thanks.

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• Sorting Algorithms

  - by MarkPearl

  General Every time I go back to university I find myself wading through sorting algorithms and their implementation in C++. Up to now I haven’t really appreciated their true value. However as I discovered this last week with Dictionaries in C# – having a knowledge of some basic programming principles can greatly improve the performance of a system and make one think twice about how to tackle a problem. I’m going to cover briefly in this post the following: Selection Sort Insertion Sort Shellsort Quicksort Mergesort Heapsort (not complete) Selection Sort Array based selection sort is a simple approach to sorting an unsorted array. Simply put, it repeats two basic steps to achieve a sorted collection. It starts with a collection of data and repeatedly parses it, each time sorting out one element and reducing the size of the next iteration of parsed data by one. So the first iteration would go something like this… Go through the entire array of data and find the lowest value Place the value at the front of the array The second iteration would go something like this… Go through the array from position two (position one has already been sorted with the smallest value) and find the next lowest value in the array. Place the value at the second position in the array This process would be completed until the entire array had been sorted. A positive about selection sort is that it does not make many item movements. In fact, in a worst case scenario every items is only moved once. Selection sort is however a comparison intensive sort. If you had 10 items in a collection, just to parse the collection you would have 10+9+8+7+6+5+4+3+2=54 comparisons to sort regardless of how sorted the collection was to start with. If you think about it, if you applied selection sort to a collection already sorted, you would still perform relatively the same number of iterations as if it was not sorted at all. Many of the following algorithms try and reduce the number of comparisons if the list is already sorted – leaving one with a best case and worst case scenario for comparisons. Likewise different approaches have different levels of item movement. Depending on what is more expensive, one may give priority to one approach compared to another based on what is more expensive, a comparison or a item move. Insertion Sort Insertion sort tries to reduce the number of key comparisons it performs compared to selection sort by not “doing anything” if things are sorted. Assume you had an collection of numbers in the following order… 10 18 25 30 23 17 45 35 There are 8 elements in the list. If we were to start at the front of the list – 10 18 25 & 30 are already sorted. Element 5 (23) however is smaller than element 4 (30) and so needs to be repositioned. We do this by copying the value at element 5 to a temporary holder, and then begin shifting the elements before it up one. So… Element 5 would be copied to a temporary holder 10 18 25 30 23 17 45 35 – T 23 Element 4 would shift to Element 5 10 18 25 30 30 17 45 35 – T 23 Element 3 would shift to Element 4 10 18 25 25 30 17 45 35 – T 23 Element 2 (18) is smaller than the temporary holder so we put the temporary holder value into Element 3. 10 18 23 25 30 17 45 35 – T 23   We now have a sorted list up to element 6. And so we would repeat the same process by moving element 6 to a temporary value and then shifting everything up by one from element 2 to element 5. As you can see, one major setback for this technique is the shifting values up one – this is because up to now we have been considering the collection to be an array. If however the collection was a linked list, we would not need to shift values up, but merely remove the link from the unsorted value and “reinsert” it in a sorted position. Which would reduce the number of transactions performed on the collection. So.. Insertion sort seems to perform better than selection sort – however an implementation is slightly more complicated. This is typical with most sorting algorithms – generally, greater performance leads to greater complexity. Also, insertion sort performs better if a collection of data is already sorted. If for instance you were handed a sorted collection of size n, then only n number of comparisons would need to be performed to verify that it is sorted. It’s important to note that insertion sort (array based) performs a number item moves – every time an item is “out of place” several items before it get shifted up. Shellsort – Diminishing Increment Sort So up to now we have covered Selection Sort & Insertion Sort. Selection Sort makes many comparisons and insertion sort (with an array) has the potential of making many item movements. Shellsort is an approach that takes the normal insertion sort and tries to reduce the number of item movements. In Shellsort, elements in a collection are viewed as sub-collections of a particular size. Each sub-collection is sorted so that the elements that are far apart move closer to their final position. Suppose we had a collection of 15 elements… 10 20 15 45 36 48 7 60 18 50 2 19 43 30 55 First we may view the collection as 7 sub-collections and sort each sublist, lets say at intervals of 7 10 60 55 – 20 18 – 15 50 – 45 2 – 36 19 – 48 43 – 7 30 10 55 60 – 18 20 – 15 50 – 2 45 – 19 36 – 43 48 – 7 30 (Sorted) We then sort each sublist at a smaller inter – lets say 4 10 55 60 18 – 20 15 50 2 – 45 19 36 43 – 48 7 30 10 18 55 60 – 2 15 20 50 – 19 36 43 45 – 7 30 48 (Sorted) We then sort elements at a distance of 1 (i.e. we apply a normal insertion sort) 10 18 55 60 2 15 20 50 19 36 43 45 7 30 48 2 7 10 15 18 19 20 30 36 43 45 48 50 55 (Sorted) The important thing with shellsort is deciding on the increment sequence of each sub-collection. From what I can tell, there isn’t any definitive method and depending on the order of your elements, different increment sequences may perform better than others. There are however certain increment sequences that you may want to avoid. An even based increment sequence (e.g. 2 4 8 16 32 …) should typically be avoided because it does not allow for even elements to be compared with odd elements until the final sort phase – which in a way would negate many of the benefits of using sub-collections. The performance on the number of comparisons and item movements of Shellsort is hard to determine, however it is considered to be considerably better than the normal insertion sort. Quicksort Quicksort uses a divide and conquer approach to sort a collection of items. The collection is divided into two sub-collections – and the two sub-collections are sorted and combined into one list in such a way that the combined list is sorted. The algorithm is in general pseudo code below… Divide the collection into two sub-collections Quicksort the lower sub-collection Quicksort the upper sub-collection Combine the lower & upper sub-collection together As hinted at above, quicksort uses recursion in its implementation. The real trick with quicksort is to get the lower and upper sub-collections to be of equal size. The size of a sub-collection is determined by what value the pivot is. Once a pivot is determined, one would partition to sub-collections and then repeat the process on each sub collection until you reach the base case. With quicksort, the work is done when dividing the sub-collections into lower & upper collections. The actual combining of the lower & upper sub-collections at the end is relatively simple since every element in the lower sub-collection is smaller than the smallest element in the upper sub-collection. Mergesort With quicksort, the average-case complexity was O(nlog2n) however the worst case complexity was still O(N*N). Mergesort improves on quicksort by always having a complexity of O(nlog2n) regardless of the best or worst case. So how does it do this? Mergesort makes use of the divide and conquer approach to partition a collection into two sub-collections. It then sorts each sub-collection and combines the sorted sub-collections into one sorted collection. The general algorithm for mergesort is as follows… Divide the collection into two sub-collections Mergesort the first sub-collection Mergesort the second sub-collection Merge the first sub-collection and the second sub-collection As you can see.. it still pretty much looks like quicksort – so lets see where it differs… Firstly, mergesort differs from quicksort in how it partitions the sub-collections. Instead of having a pivot – merge sort partitions each sub-collection based on size so that the first and second sub-collection of relatively the same size. This dividing keeps getting repeated until the sub-collections are the size of a single element. If a sub-collection is one element in size – it is now sorted! So the trick is how do we put all these sub-collections together so that they maintain their sorted order. Sorted sub-collections are merged into a sorted collection by comparing the elements of the sub-collection and then adjusting the sorted collection. Lets have a look at a few examples… Assume 2 sub-collections with 1 element each 10 & 20 Compare the first element of the first sub-collection with the first element of the second sub-collection. Take the smallest of the two and place it as the first element in the sorted collection. In this scenario 10 is smaller than 20 so 10 is taken from sub-collection 1 leaving that sub-collection empty, which means by default the next smallest element is in sub-collection 2 (20). So the sorted collection would be 10 20 Lets assume 2 sub-collections with 2 elements each 10 20 & 15 19 So… again we would Compare 10 with 15 – 10 is the winner so we add it to our sorted collection (10) leaving us with 20 & 15 19 Compare 20 with 15 – 15 is the winner so we add it to our sorted collection (10 15) leaving us with 20 & 19 Compare 20 with 19 – 19 is the winner so we add it to our sorted collection (10 15 19) leaving us with 20 & _ 20 is by default the winner so our sorted collection is 10 15 19 20. Make sense? Heapsort (still needs to be completed) So by now I am tired of sorting algorithms and trying to remember why they were so important. I think every year I go through this stuff I wonder to myself why are we made to learn about selection sort and insertion sort if they are so bad – why didn’t we just skip to Mergesort & Quicksort. I guess the only explanation I have for this is that sometimes you learn things so that you can implement them in future – and other times you learn things so that you know it isn’t the best way of implementing things and that you don’t need to implement it in future. Anyhow… luckily this is going to be the last one of my sorts for today. The first step in heapsort is to convert a collection of data into a heap. After the data is converted into a heap, sorting begins… So what is the definition of a heap? If we have to convert a collection of data into a heap, how do we know when it is a heap and when it is not? The definition of a heap is as follows: A heap is a list in which each element contains a key, such that the key in the element at position k in the list is at least as large as the key in the element at position 2k +1 (if it exists) and 2k + 2 (if it exists). Does that make sense? At first glance I’m thinking what the heck??? But then after re-reading my notes I see that we are doing something different – up to now we have really looked at data as an array or sequential collection of data that we need to sort – a heap represents data in a slightly different way – although the data is stored in a sequential collection, for a sequential collection of data to be in a valid heap – it is “semi sorted”. Let me try and explain a bit further with an example… Example 1 of Potential Heap Data Assume we had a collection of numbers as follows 1[1] 2[2] 3[3] 4[4] 5[5] 6[6] For this to be a valid heap element with value of 1 at position [1] needs to be greater or equal to the element at position [3] (2k +1) and position [4] (2k +2). So in the above example, the collection of numbers is not in a valid heap. Example 2 of Potential Heap Data Lets look at another collection of numbers as follows 6[1] 5[2] 4[3] 3[4] 2[5] 1[6] Is this a valid heap? Well… element with the value 6 at position 1 must be greater or equal to the element at position [3] and position [4]. Is 6 > 4 and 6 > 3? Yes it is. Lets look at element 5 as position 2. It must be greater than the values at [4] & [5]. Is 5 > 3 and 5 > 2? Yes it is. If you continued to examine this second collection of data you would find that it is in a valid heap based on the definition of a heap.

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• C++: Calling class functions within a switch

  - by user1446002

  i've been trying to study for my finals by practicing classes and inheritance, this is what I've come up with so far for inheritance and such however I'm unsure how to fix the error occuring below. #include<iostream> #include<iomanip> #include<cmath> #include<string.h> using namespace std; //BASE CLASS DEFINITION class hero { protected: string name; string mainAttr; int xp; double hp; double mana; double armour; int range; double attkDmg; bool attkType; public: void dumpData(); void getName(); void getMainAttr(); void getAttkData(); void setAttkData(string); void setBasics(string, string, double, double, double); void levelUp(); }; //CLASS FUNCTIONS void hero::dumpData() { cout << "Name: " << name << endl; cout << "Main Attribute: " << mainAttr << endl; cout << "XP: " << xp << endl; cout << "HP: " << hp << endl; cout << "Mana: " << mana << endl; cout << "Armour: " << armour << endl; cout << "Attack Range: " << range << endl; cout << "Attack Damage: " << attkDmg << endl; cout << "Attack Type: " << attkType << endl << endl; } void hero::getName() { cout << "Name: " << name << endl; } void hero::getMainAttr() { cout << "Main Attribute: " << mainAttr << endl; } void hero::getAttkData() { cout << "Attack Range: " << range << endl; cout << "Attack Damage: " << attkDmg << endl; cout << "Attack Type: " << attkType << endl; } void hero::setAttkData(string attr) { int choice = 0; if (attr == "Strength") { choice = 1; } if (attr == "Agility") { choice = 2; } if (attr == "Intelligence") { choice = 3; } switch (choice) { case 1: range = 128; attkDmg = 80.0; attkType = 0; break; case 2: range = 350; attkDmg = 60.0; attkType = 0; break; case 3: range = 600; attkDmg = 35.0; attkType = 1; break; default: break; } } void hero::setBasics(string heroName, string attribute, double health, double mp, double armourVal) { name = heroName; mainAttr = attribute; hp = health; mana = mp; armour = armourVal; } void hero::levelUp() { xp = 0; hp = hp + (hp * 0.1); mana = mana + (mana * 0.1); armour = armour + ((armour*0.1) + 1); attkDmg = attkDmg + (attkDmg * 0.05); } //INHERITED CLASS DEFINITION class neutHero : protected hero { protected: string drops; int xpGain; public: int giveXP(int); void dropItems(); }; //INHERITED CLASS FUNCTIONS int neutHero::giveXP(int exp) { xp += exp; } void neutHero::dropItems() { cout << name << " has dropped the following items: " << endl; cout << drops << endl; } /* END OF OO! */ //FUNCTION PROTOTYPES void dispMenu(); int main() { int exit=0, choice=0, mainAttrChoice=0, heroCreated=0; double health, mp, armourVal; string heroName, attribute; do { dispMenu(); cin >> choice; switch (choice) { case 1: system("cls"); cout << "Please enter your hero name: "; cin >> heroName; cout << "\nPlease enter your primary attribute\n"; cout << "1. Strength\n" << "2. Agility\n" << "3. Intelligence\n"; cin >> mainAttrChoice; switch (mainAttrChoice) { case 1: attribute = "Strength"; health = 750; mp = 150; armourVal = 2; break; case 2: attribute = "Agility"; health = 550; mp = 200; armourVal = 6; break; case 3: attribute = "Intelligence"; health = 450; mp = 450; armourVal = 1; break; default: cout << "Choice invalid, please try again."; exit = 1; break; hero player; player.setBasics(heroName, attribute, health, mp, armourVal); player.setAttkData(attribute); heroCreated=1; system("cls"); cout << "Your hero has been created!\n\n"; player.dumpData(); system("pause"); break; } case 2: system("cls"); if (heroCreated == 1) { cout << "Your hero has been detailed below.\n\n"; **player.dumpData(); //ERROR OCCURS HERE !** system("pause"); } else { cout << "You have not created a hero please exit this prompt " "and press 1 on the menu to create a hero."; } break; case 3: system("cls"); cout << "Still Under Development"; system("pause"); break; case 4: system("cls"); exit = 1; break; default: cout << "Your command has not been recognised, please try again.\n"; system("pause"); break; } } while (exit != 1); system("pause"); return 0; } void dispMenu() { system("cls"); cout << "1. Create New Hero\n" "2. View Current Hero\n" "3. Fight Stuff\n" "4. Exit\n\n" "Enter your choice: "; } However upon compilation I get the following errors: 220 `player' undeclared (first use this function) Unsure exactly how to fix it as I've only recently started using OO approach. The error has a comment next to it above and is in case 2 in the main. Cheers guys.

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• How to get data from dynamically created EditText views and insert it into an array?

  - by Snwspeckle

  So basically what I need my program to do at this point is that when I click the submit button, I need to loop through each dynamic row of the ListView and grab the value in the EditText view and then insert that into an array which I will do further calculations after. Here is my code right now. package com.hello_world; import java.util.ArrayList; import com.hello_world.ByteInputActivity.MyAdapter.ViewHolder; import android.app.Activity; import android.content.Context; import android.os.Bundle; import android.util.Log; import android.view.KeyEvent; import android.view.LayoutInflater; import android.view.View; import android.view.View.OnFocusChangeListener; import android.view.View.OnKeyListener; import android.view.ViewGroup; import android.widget.BaseAdapter; import android.widget.Button; import android.widget.EditText; import android.widget.ListView; import android.widget.TextView; public class ByteInputActivity extends Activity { private ListView myList; private MyAdapter myAdapter; private Integer resQuestions; private Integer indexVal = 0; private View caption; ViewHolder holder; ArrayList<Integer> intArrayList = new ArrayList<Integer>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.fieldlist); //Gets number of questions from MainActivity Bundle extras = getIntent().getExtras(); if(extras !=null) { resQuestions = extras.getInt("index"); } myList = (ListView) findViewById(R.id.FieldList); myList.setItemsCanFocus(true); myAdapter = new MyAdapter(); myList.setAdapter(myAdapter); Button submit = (Button) findViewById(R.id.btn_New); submit.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { for (int i = 0; i < myList.getCount() ; i++) { View vListSortOrder; vListSortOrder = myList.getChildAt(i); String temp = holder.caption.getText().toString(); Log.e("VALUES", "" +temp); } } }); } public class MyAdapter extends BaseAdapter { private LayoutInflater mInflater; public ArrayList myItems = new ArrayList(); public MyAdapter() { mInflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE); for (int i = 0; i < resQuestions; i++) { ListItem listItem = new ListItem(); listItem.caption = "Index " + i; listItem.indexText = "Index " + i; myItems.add(listItem); indexVal += 1; } notifyDataSetChanged(); } public int getCount() { return myItems.size(); } public Object getItem(int position) { return position; } public long getItemId(int position) { return position; } public View getView(int position, View convertView, ViewGroup parent) { if (convertView == null) { holder = new ViewHolder(); convertView = mInflater.inflate(R.layout.item, null); holder.indexText = (TextView) convertView .findViewById(R.id.textView1); holder.caption = (EditText) convertView .findViewById(R.id.ItemCaption); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); } //Fill EditText with the value you have in data source holder.caption.setText(""); holder.caption.setId(position); holder.indexText.setText("Index " + position); holder.indexText.setId(position); //we need to update adapter once we finish with editing holder.caption.setOnFocusChangeListener(new OnFocusChangeListener() { public void onFocusChange(View v, boolean hasFocus) { if (!hasFocus){ final int position = v.getId(); final EditText Caption = (EditText) v; myItems.set(position, Caption.getText().toString()); } } }); return convertView; } class ViewHolder { EditText caption; TextView indexText; } class ListItem { String caption; String indexText; } } }

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• RAID 5 configuration and future expansion

  - by Alexis Hirst

  hi, I am building a PC to act as a file server among other things, and I was wondering whether it is a good idea to create 2 partitions on the RAID 5 array, one for OS one for data, or to have a separate disk for OS and use array for data. Also, one day i may want to add another disk to the array, so would there be any issues if I had the OS partition on the RAID5 array when it came to resizing the data partition?

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• dmidecode showing more ram slots than available?

  - by Jestep

  I have some failing RAM in a server and I ran dmidecode to figure out what tyoe of RAM I needed to replace it with. The server has 6 RAM slots, 4 of which are in use. When I run dmidecode this is what I get. dmidecode 2.10 SMBIOS 2.4 present. Handle 0x001F, DMI type 17, 27 bytes Memory Device Array Handle: 0x001E Error Information Handle: No Error Total Width: 72 bits Data Width: 64 bits Size: 2048 MB Form Factor: DIMM Set: 1 Locator: JXXX Bank Locator: DIMM 00 Type: DDR2 Type Detail: Synchronous Speed: 667 MHz Manufacturer: Not Specified Serial Number: Not Specified Asset Tag: Not Specified Part Number: Not Specified Handle 0x0020, DMI type 17, 27 bytes Memory Device Array Handle: 0x001E Error Information Handle: No Error Total Width: 72 bits Data Width: 64 bits Size: 2048 MB Form Factor: DIMM Set: 1 Locator: JXXX Bank Locator: DIMM 01 Type: DDR2 Type Detail: Synchronous Speed: 667 MHz Manufacturer: Not Specified Serial Number: Not Specified Asset Tag: Not Specified Part Number: Not Specified Handle 0x0021, DMI type 17, 27 bytes Memory Device Array Handle: 0x001E Error Information Handle: No Error Total Width: Unknown Data Width: Unknown Size: No Module Installed Form Factor: DIMM Set: 1 Locator: JXXX Bank Locator: DIMM 02 Type: DDR2 Type Detail: Synchronous Speed: 667 MHz Manufacturer: Not Specified Serial Number: Not Specified Asset Tag: Not Specified Part Number: Not Specified Handle 0x0022, DMI type 17, 27 bytes Memory Device Array Handle: 0x001E Error Information Handle: No Error Total Width: Unknown Data Width: Unknown Size: No Module Installed Form Factor: DIMM Set: 1 Locator: JXXX Bank Locator: DIMM 03 Type: DDR2 Type Detail: Synchronous Speed: 667 MHz Manufacturer: Not Specified Serial Number: Not Specified Asset Tag: Not Specified Part Number: Not Specified Handle 0x0023, DMI type 17, 27 bytes Memory Device Array Handle: 0x001E Error Information Handle: No Error Total Width: 72 bits Data Width: 64 bits Size: 2048 MB Form Factor: DIMM Set: 1 Locator: JXXX Bank Locator: DIMM 10 Type: DDR2 Type Detail: Synchronous Speed: 667 MHz Manufacturer: Not Specified Serial Number: Not Specified Asset Tag: Not Specified Part Number: Not Specified Handle 0x0024, DMI type 17, 27 bytes Memory Device Array Handle: 0x001E Error Information Handle: No Error Total Width: 72 bits Data Width: 64 bits Size: 2048 MB Form Factor: DIMM Set: 1 Locator: JXXX Bank Locator: DIMM 11 Type: DDR2 Type Detail: Synchronous Speed: 667 MHz Manufacturer: Not Specified Serial Number: Not Specified Asset Tag: Not Specified Part Number: Not Specified Handle 0x0025, DMI type 17, 27 bytes Memory Device Array Handle: 0x001E Error Information Handle: No Error Total Width: Unknown Data Width: Unknown Size: No Module Installed Form Factor: DIMM Set: 1 Locator: JXXX Bank Locator: DIMM 12 Type: DDR2 Type Detail: Synchronous Speed: 667 MHz Manufacturer: Not Specified Serial Number: Not Specified Asset Tag: Not Specified Part Number: Not Specified Handle 0x0026, DMI type 17, 27 bytes Memory Device Array Handle: 0x001E Error Information Handle: No Error Total Width: Unknown Data Width: Unknown Size: No Module Installed Form Factor: DIMM Set: 1 Locator: JXXX Bank Locator: DIMM 13 Type: DDR2 Type Detail: Synchronous Speed: 667 MHz Manufacturer: Not Specified Serial Number: Not Specified Asset Tag: Not Specified Part Number: Not Specified Does anyone know why it would show 8 slots, with 4 empty instead of 6 slots with 2 empty? Also, but my records and by other tools, the server has 16Gb and not 8Gb in it currently. grep MemTotal /proc/meminfo MemTotal: 16435808 kB The board is a Tyan S5372-LC, running CentOS 5.4 x64. Also, my error log is showing errors in bank 6. Is there any way to determine which slot bank 6 is in via: dmidecode?

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• use Amazon EC2 tools in Capistrano to get the servers to push the code

  - by APZ

  I am trying to use EC2 tools to get all the machines with a particular tag in some type of array in /config/deploy/prod.rb file in Capistrano. Something like this: In prod.rb file: //untested command workers-array[]=$(ec2-describe-instances -F vpc-id=1234 -F tag:Env=prod -F tag:SystemType=worker) for(i=0;i<workers-array.len;i++){ role :worker-A, workers-array[i] } I am not sure how we can do this in capistrano, am new to ruby too. Guys any help on this would be really appreciated.

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• C# 4.0: Dynamic Programming

  - by Paulo Morgado

  The major feature of C# 4.0 is dynamic programming. Not just dynamic typing, but dynamic in broader sense, which means talking to anything that is not statically typed to be a .NET object. Dynamic Language Runtime The Dynamic Language Runtime (DLR) is piece of technology that unifies dynamic programming on the .NET platform, the same way the Common Language Runtime (CLR) has been a common platform for statically typed languages. The CLR always had dynamic capabilities. You could always use reflection, but its main goal was never to be a dynamic programming environment and there were some features missing. The DLR is built on top of the CLR and adds those missing features to the .NET platform. The Dynamic Language Runtime is the core infrastructure that consists of: Expression Trees The same expression trees used in LINQ, now improved to support statements. Dynamic Dispatch Dispatches invocations to the appropriate binder. Call Site Caching For improved efficiency. Dynamic languages and languages with dynamic capabilities are built on top of the DLR. IronPython and IronRuby were already built on top of the DLR, and now, the support for using the DLR is being added to C# and Visual Basic. Other languages built on top of the CLR are expected to also use the DLR in the future. Underneath the DLR there are binders that talk to a variety of different technologies: .NET Binder Allows to talk to .NET objects. JavaScript Binder Allows to talk to JavaScript in SilverLight. IronPython Binder Allows to talk to IronPython. IronRuby Binder Allows to talk to IronRuby. COM Binder Allows to talk to COM. Whit all these binders it is possible to have a single programming experience to talk to all these environments that are not statically typed .NET objects. The dynamic Static Type Let’s take this traditional statically typed code: Calculator calculator = GetCalculator(); int sum = calculator.Sum(10, 20); Because the variable that receives the return value of the GetCalulator method is statically typed to be of type Calculator and, because the Calculator type has an Add method that receives two integers and returns an integer, it is possible to call that Sum method and assign its return value to a variable statically typed as integer. Now lets suppose the calculator was not a statically typed .NET class, but, instead, a COM object or some .NET code we don’t know he type of. All of the sudden it gets very painful to call the Add method: object calculator = GetCalculator(); Type calculatorType = calculator.GetType(); object res = calculatorType.InvokeMember("Add", BindingFlags.InvokeMethod, null, calculator, new object[] { 10, 20 }); int sum = Convert.ToInt32(res); And what if the calculator was a JavaScript object? ScriptObject calculator = GetCalculator(); object res = calculator.Invoke("Add", 10, 20); int sum = Convert.ToInt32(res); For each dynamic domain we have a different programming experience and that makes it very hard to unify the code. With C# 4.0 it becomes possible to write code this way: dynamic calculator = GetCalculator(); int sum = calculator.Add(10, 20); You simply declare a variable who’s static type is dynamic. dynamic is a pseudo-keyword (like var) that indicates to the compiler that operations on the calculator object will be done dynamically. The way you should look at dynamic is that it’s just like object (System.Object) with dynamic semantics associated. Anything can be assigned to a dynamic. dynamic x = 1; dynamic y = "Hello"; dynamic z = new List<int> { 1, 2, 3 }; At run-time, all object will have a type. In the above example x is of type System.Int32. When one or more operands in an operation are typed dynamic, member selection is deferred to run-time instead of compile-time. Then the run-time type is substituted in all variables and normal overload resolution is done, just like it would happen at compile-time. The result of any dynamic operation is always dynamic and, when a dynamic object is assigned to something else, a dynamic conversion will occur. Code Resolution Method double x = 1.75; double y = Math.Abs(x); compile-time double Abs(double x) dynamic x = 1.75; dynamic y = Math.Abs(x); run-time double Abs(double x) dynamic x = 2; dynamic y = Math.Abs(x); run-time int Abs(int x) The above code will always be strongly typed. The difference is that, in the first case the method resolution is done at compile-time, and the others it’s done ate run-time. IDynamicMetaObjectObject The DLR is pre-wired to know .NET objects, COM objects and so forth but any dynamic language can implement their own objects or you can implement your own objects in C# through the implementation of the IDynamicMetaObjectProvider interface. When an object implements IDynamicMetaObjectProvider, it can participate in the resolution of how method calls and property access is done. The .NET Framework already provides two implementations of IDynamicMetaObjectProvider: DynamicObject : IDynamicMetaObjectProvider The DynamicObject class enables you to define which operations can be performed on dynamic objects and how to perform those operations. For example, you can define what happens when you try to get or set an object property, call a method, or perform standard mathematical operations such as addition and multiplication. ExpandoObject : IDynamicMetaObjectProvider The ExpandoObject class enables you to add and delete members of its instances at run time and also to set and get values of these members. This class supports dynamic binding, which enables you to use standard syntax like sampleObject.sampleMember, instead of more complex syntax like sampleObject.GetAttribute("sampleMember").

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• Doctrine Fatal Error - Unknown relation alias

  - by Sadiqur Rahman

  I am getting following error message: Doctrine_Table_Exception: Unknown relation alias shoesTable in /home/public_html/projects/giftshoes/system/database/doctrine/Doctrine/Relation/Parser.php on line 237 I am using doctrine 1.2.2 with Codeigniter My Code is below: (BaseShoes.php and Shoes.php is auto generated) ------------BaseShoes------------ <?php // Connection Component Binding Doctrine_Manager::getInstance()->bindComponent('Shoes', 'sadiqsof_giftshoes'); /** * BaseShoes * * This class has been auto-generated by the Doctrine ORM Framework * * @property integer $sku * @property string $name * @property string $keywords * @property string $description * @property string $manufacturer * @property float $sale_price * @property float $price * @property string $url * @property string $image * @property string $category * @property Doctrine_Collection $Viewes * * @package ##PACKAGE## * @subpackage ##SUBPACKAGE## * @author ##NAME## <##EMAIL##> * @version SVN: $Id: Builder.php 6820 2009-11-30 17:27:49Z jwage $ */ abstract class BaseShoes extends Doctrine_Record { public function setTableDefinition() { $this->setTableName('shoes'); $this->hasColumn('sku', 'integer', 4, array( 'type' => 'integer', 'fixed' => 0, 'unsigned' => false, 'primary' => true, 'autoincrement' => false, 'length' => '4', )); $this->hasColumn('name', 'string', 255, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '255', )); $this->hasColumn('keywords', 'string', 255, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '255', )); $this->hasColumn('description', 'string', null, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('manufacturer', 'string', 20, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '20', )); $this->hasColumn('sale_price', 'float', null, array( 'type' => 'float', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('price', 'float', null, array( 'type' => 'float', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('url', 'string', null, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('image', 'string', null, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('category', 'string', 50, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '50', )); } public function setUp() { parent::setUp(); $this->hasMany('Viewes', array( 'local' => 'sku', 'foreign' => 'sku')); } } --------------ShoesTable-------- <?php class ShoesTable extends Doctrine_Table { function getAllShoes($from = 0, $total = 15) { $q = Doctrine_Query::create() ->from('Shoes') ->limit($total) ->offset($from); return $q->execute(array(), Doctrine::HYDRATE_ARRAY); } } ---------------Shoes Model----------------- <?php /** * Shoes * * This class has been auto-generated by the Doctrine ORM Framework * * @package ##PACKAGE## * @subpackage ##SUBPACKAGE## * @author ##NAME## <##EMAIL##> * @version SVN: $Id: Builder.php 6820 2009-11-30 17:27:49Z jwage $ */ class Shoes extends BaseShoes { function __construct() { parent::__construct(); $this->shoesTable = Doctrine::getTable('Shoes'); } function getAllShoes() { return $this->shoesTable->getAllShoes(); } }

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• Lawler's Algorithm Implementation Assistance

  - by Richard Knop

  Here is my implemenation of Lawler's algorithm in PHP (I know... but I'm used to it): <?php $jobs = array(1, 2, 3, 4, 5, 6); $jobsSubset = array(2, 5, 6); $n = count($jobs); $processingTimes = array(2, 3, 4, 3, 2, 1); $dueDates = array(3, 15, 9, 7, 11, 20); $optimalSchedule = array(); foreach ($jobs as $j) { $optimalSchedule[] = 0; } $dicreasedCardinality = array(); for ($i = $n; $i >= 1; $i--) { $x = 0; $max = 0; // loop through all jobs for ($j = 0; $j < $i; $j++) { // ignore if $j already is in the $dicreasedCardinality array if (false === in_array($j, $dicreasedCardinality)) { // if the job has no succesor in $jobsSubset if (false === isset($jobs[$j+1]) || false === in_array($jobs[$j+1], $jobsSubset)) { // here I find an array index of a job with the maximum due date // amongst jobs with no sucessor in $jobsSubset if ($x < $dueDates[$j]) { $x = $dueDates[$j]; $max = $j; } } } } // move the job at the end of $optimalSchedule $optimalSchedule[$i-1] = $jobs[$max]; // decrease the cardinality of $jobs $dicreasedCardinality[] = $max; } print_r($optimalSchedule); Now the above returns an optimal schedule like this: Array ( [0] => 1 [1] => 1 [2] => 1 [3] => 3 [4] => 2 [5] => 6 ) Which doesn't seem right to me. The problem might be with my implementation of the algorithm because I am not sure I understand it correctly. I used this source to implement it: http://www.google.com/books?id=aSiBs6PDm9AC&pg=PA166&dq=lawler%27s+algorithm+code&lr=&hl=sk&cd=4#v=onepage&q=&f=false The description there is a little confusing. For example, I didn't quite get how is the subset D defined (I guess it is arbitrary). Could anyone help me out with this? I have been trying to find some sources with simpler explanation of the algorithm but all sources I found were even more complicated (with math proofs and such) so I am stuck with the link above. Yes, this is a homework, if it wasn't obvious. I still have few weeks to crack this but I have spent few days already trying to get how exactly this algorithm works with no success so I don't think I will get any brighter during that time.

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• Please Explain Drupal schema and drupal_write_record

  - by Aaron

  Hi. A few questions. 1) Where is the best place to populate a new database table when a module is first installed, enabled? I need to go and get some data from an external source and want to do it transparently when the user installs/enables my custom module. I create the schema in {mymodule}_schema(), do drupal_install_schema({tablename}); in hook_install. Then I try to populate the table in hook_enable using drupal_write_record. I confirmed the table was created, I get no errors when hook_enable executes, but when I query the new table, I get no rows back--it's empty. Here's one variation of the code I've tried: /** * Implementation of hook_schema() */ function ncbi_subsites_schema() { // we know it's MYSQL, so no need to check $schema['ncbi_subsites_sites'] = array( 'description' => 'The base table for subsites', 'fields' => array( 'site_id' => array( 'description' => 'Primary id for site', 'type' => 'serial', 'unsigned' => TRUE, 'not null' => TRUE, ), // end site_id 'title' => array( 'description' => 'The title of the subsite', 'type' => 'varchar', 'length' => 255, 'not null' => TRUE, 'default' => '', ), //end title field 'url' => array( 'description' => 'The URL of the subsite in Production', 'type' => 'varchar', 'length' => 255, 'default' => '', ), //end url field ), //end fields 'unique keys' => array( 'site_id'=> array('site_id'), 'title' => array('title'), ), //end unique keys 'primary_key' => array('site_id'), ); // end schema return $schema; } Here's hook_install: function ncbi_subsites_install() { drupal_install_schema('ncbi_subsites'); } Here's hook_enable: function ncbi_subsites_enable() { drupal_get_schema('ncbi_subsites_site'); // my helper function to get data for table (not shown) $subsites = ncbi_subsites_get_subsites(); foreach( $subsites as $name=>$attrs ) { $record = new stdClass(); $record->title = $name; $record->url = $attrs['homepage']; drupal_write_record( 'ncbi_subsites_sites', $record ); } } Can someone tell me what I'm missing?

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• Frameskipping in Android gameloop causing choppy sprites (Open GL ES 2.0)

  - by user22241

  I have written a simple 2d platform game for Android and am wondering how one deals with frame-skipping? Are there any alternatives? Let me explain further. So, my game loop allows for the rendering to be skipped if game updates and rendering do not fit into my fixed time-slice (16.667ms). This allows my game to run at identically perceived speeds on different devices. And this works great, things do run at the same speed. However, when the gameloop skips a render call for even one frame, the sprite glitches. And thinking about it, why wouldn't it? You're seeing a sprite move say, an average of 10 pixels every 1.6 seconds, then suddenly, there is a pause of 3.2ms, and the sprite then appears to jump 20 pixels. When this happens 3 or 4 times in close succession, the result is very ugly and not something I want in my game. Therfore, my question is how does one deal with these 'pauses' and 'jumps' - I've read every article on game loops I can find (see below) and my loops are even based off of code from these articles. The articles specifically mention frame skipping but they don't make any reference to how to deal with visual glitches that result from it. I've attempted various game-loops. My loop must have a mechanism in-place to allow rendering to be skipped to keep game-speed constant across multiple devices (or alternative, if one exists) I've tried interpolation but this doesn't eliminate this specific problem (although it looks like it may mitigate the issue slightly as when it eventually draws the sprite it 'moves it back' between the old and current positions so the 'jump' isn't so big. I've also tried a form of extrapolation which does seem to keep things smooth considerably, but I find it to be next to completely useless because it plays havoc with my collision detection (even when drawing with a 'display only' coordinate - see extrapolation-breaks-collision-detection) I've tried a loop that uses Thread.sleep when drawing / updating completes with time left over, no frame skipping in this one, again fairly smooth, but runs differently on different devices so no good. And I've tried spawning my own, third thread for logic updates, but this, was extremely messy to deal with and the performance really wasn't good. (upon reading tons of forums, most people seem to agree a 2 thread loops ( so UI and GL threads) is safer / easier). Now if I remove frame skipping, then all seems to run nice and smooth, with or without inter/extrapolation. However, this isn't an option because the game then runs at different speeds on different devices as it falls behind from not being able to render fast enough. I'm running logic at 60 Ticks per second and rendering as fast as I can. I've read, as far as I can see every article out there, I've tried the loops from My Secret Garden and Fix your timestep. I've also read: Against the grain deWITTERS Game Loop Plus various other articles on Game-loops. A lot of the others are derived from the above articles or just copied word for word. These are all great, but they don't touch on the issues I'm experiencing. I really have tried everything I can think of over the course of a year to eliminate these glitches to no avail, so any and all help would be appreciated. A couple of examples of my game loops (Code follows): From My Secret Room public void onDrawFrame(GL10 gl) { //Rre-set loop back to 0 to start counting again loops=0; while(System.currentTimeMillis() > nextGameTick && loops < maxFrameskip) { SceneManager.getInstance().getCurrentScene().updateLogic(); nextGameTick += skipTicks; timeCorrection += (1000d / ticksPerSecond) % 1; nextGameTick += timeCorrection; timeCorrection %= 1; loops++; } extrapolation = (float)(System.currentTimeMillis() + skipTicks - nextGameTick) / (float)skipTicks; render(extrapolation); } And from Fix your timestep double t = 0.0; double dt2 = 0.01; double currentTime = System.currentTimeMillis()*0.001; double accumulator = 0.0; double newTime; double frameTime; @Override public void onDrawFrame(GL10 gl) { newTime = System.currentTimeMillis()*0.001; frameTime = newTime - currentTime; if ( frameTime > (dt*5)) //Allow 5 'skips' frameTime = (dt*5); currentTime = newTime; accumulator += frameTime; while ( accumulator >= dt ) { SceneManager.getInstance().getCurrentScene().updateLogic(); previousState = currentState; accumulator -= dt; } interpolation = (float) (accumulator / dt); render(interpolation); }

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• NSArrays in NSArrays. A pointer problem?

  - by RyJ

  I believe my problem involves pointers, a concept I often struggle with, but here's what I'm trying to do. I have six NSArrays. I want an additional NSArray comprised of these six arrays, so: self.arr1 = [NSArray array]; self.arr2 = [NSArray array]; self.arr3 = [NSArray array]; self.arr4 = [NSArray array]; self.arr5 = [NSArray array]; self.arr6 = [NSArray array]; NSArray *containerArray = [[NSArray alloc] initWithObjects:self.arr1, ... etc, nil]; Whenever I update one of the first 6 NSArrays, I want the object updated in containerArray. (I know I'm using an NSArray and not an NSMutableArray, when I update the arrays I create a new one and assign it to the instance variable). Currently, any manipulation of arr1 is not reflected in [containerArray objectAtIndex:0].

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• abstract data type list. . .

  - by aldrin

  A LIST is an ordered collection of items where items may be inserted anywhere in the list. Implement a LIST using an array as follows: struct list { int *items; // pointer to the array int size; // actual size of the array int count; // number of items in the array }; typedef struct list *List; // pointer to the structure Implement the following functions: a) List newList(int size); - will create a new List and return its pointer. Allocate space for the structure, allocate space for the array, then initialize size and count, return the pointer. b) void isEmpty(List list); c) void display(List list); d) int contains(List list, int item); e) void remove(List list, int i) ; f) void insertAfter(List list,int item, int i); g) void addEnd(List list,int item) - add item at the end of the list – simply store the data at position count, then increment count. If the array is full, allocate an array twice as big as the original. count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 addEnd(list,40) will result to count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 40 h) void addFront(List list,int item) - shift all elements to the right so that the item can be placed at position 0, then increment count. Bonus: if the array is full, allocate an array twice as big as the original. count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 addFront(list,40) will result to count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 10 15 20 30 i) void removeFront(List list) - shift all elements to the left and decrement count; count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 10 15 20 30 removeFront(list) will result to count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 j) void remove(List list,int item) - get the index of the item in the list and then shift all elements to the count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 10 15 20 30 remove(list,10) will result to count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 15 20 30

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• Does NSArray:lastObject return an autoreleased object?

  - by Kyle

  I'm working on an iPhone project where I would like to retrieve an object from an NSMutableArray, remove the object from the array and then use it later. The code looks something like this: NSMutableArray * array; // fill the array NSObject * obj = [array lastObject]; [array removeLastObject]; // do something with obj (in the same function) array is the only entity with a retain on the object that is being accessed. Is this safe to do? I would assume that this would only work if lastObject autoreleased the object which is something that I can't figure out if it does.

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• Is this way of storing typed objects in memory good?

  - by Pindatjuh

  This is an "is this okay, or can it be done better" question. Topic: Storing typed objects in memory. Background information: I'm building a compiler for the x86-32 platform for my language. My goal includes typed objects. Idea: Every primitive is a semi-class (it can be used as if it was a normal class, but it's stored more compact). Every class is represented by primitives and some meta-data (containing class-properties, inheritance stuff, etc.). The meta-data is complex: it doesn't use fields but instead context-switches. For primitives, the meta-data is very small, compared to a "real" class, which is alot bigger. This enables another idea that "primitives are objects", in my language, which I found nessecairy. Example: If I have an array of 32 booleans, then the pure content of this array is exactly 4 byte (32 bits of booleans). The meta-data will contain flags that the type is an array of booleans, which contains 32 entries. The meta-data is very compacted, on bit-level: using a sort of "packing" mechanism, which is read by a FSM at runtime, when doing inspection of the type (like when passing the object to methods for checking, etc.) For instance (read from left to right, top to bottom, remember vertical possition when going to the right, and check nearest column header for meaning of switch): Primitive? Array? Type-Meta 1 Byte? || Size (1 byte) 1 1 [...] 1 [...] done 0 2 Bytes? || Size (2 bytes) 1 [...] done || Size (4 bytes) 0 [...] done Integer? 1 Byte? 2 Bytes? 0 1 0 1 done 1 done 0 done Boolean? Byte? 0 1 0 done 1 done More-Primitives 0 .... Class-Stuff (Huge) 0 ... (After reaching done the data is inserted. || = byte alignement. [...] is variable sized. ... is not described here, for simplicity. And let's call them cost-based-data-structures.) For an array of 32 booleans containing all true values, the memory for this type would be (read top-down): 1 Primitive 1 Array 1 ArrayType: Primitive 0 Not-Array 0 Not-Integer 1 Boolean 0 Not-Byte (thus bit) 1 Integer Size: 1 Byte 00100000 Array size 11111111 11111111 11111111 11111111 Data Thus, 8 bytes represent 32 booleans in an array: 11100101 00100000 11111111 11111111 11111111 11111111 Is this okay, or can it be done better?

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• Extreme Optimization – Numerical Algorithm Support

  - by JoshReuben

  Function Delegates Many calculations involve the repeated evaluation of one or more user-supplied functions eg Numerical integration. The EO MathLib provides delegate types for common function signatures and the FunctionFactory class can generate new delegates from existing ones. RealFunction delegate - takes one Double parameter – can encapsulate most of the static methods of the System.Math class, as well as the classes in the Extreme.Mathematics.SpecialFunctions namespace: var sin = new RealFunction(Math.Sin); var result = sin(1); BivariateRealFunction delegate - takes two Double parameters: var atan2 = new BivariateRealFunction (Math.Atan2); var result = atan2(1, 2); TrivariateRealFunction delegate – represents a function takes three Double arguments ParameterizedRealFunction delegate - represents a function taking one Integer and one Double argument that returns a real number. The Pow method implements such a function, but the arguments need order re-arrangement: static double Power(int exponent, double x) { return ElementaryFunctions.Pow(x, exponent); } ... var power = new ParameterizedRealFunction(Power); var result = power(6, 3.2); A ComplexFunction delegate - represents a function that takes an Extreme.Mathematics.DoubleComplex argument and also returns a complex number. MultivariateRealFunction delegate - represents a function that takes an Extreme.Mathematics.LinearAlgebra.Vector argument and returns a real number. MultivariateVectorFunction delegate - represents a function that takes a Vector argument and returns a Vector. FastMultivariateVectorFunction delegate - represents a function that takes an input Vector argument and an output Matrix argument – avoiding object construction  The FunctionFactory class RealFromBivariateRealFunction and RealFromParameterizedRealFunction helper methods - transform BivariateRealFunction or a ParameterizedRealFunction into a RealFunction delegate by fixing one of the arguments, and treating this as a new function of a single argument. var tenthPower = FunctionFactory.RealFromParameterizedRealFunction(power, 10); var result = tenthPower(x); Note: There is no direct way to do this programmatically in C# - in F# you have partial value functions where you supply a subset of the arguments (as a travelling closure) that the function expects. When you omit arguments, F# generates a new function that holds onto/remembers the arguments you passed in and "waits" for the other parameters to be supplied. let sumVals x y = x + y     let sumX = sumVals 10     // Note: no 2nd param supplied.     // sumX is a new function generated from partially applied sumVals.     // ie "sumX is a partial application of sumVals." let sum = sumX 20     // Invokes sumX, passing in expected int (parameter y from original)  val sumVals : int -> int -> int val sumX : (int -> int) val sum : int = 30 RealFunctionsToVectorFunction and RealFunctionsToFastVectorFunction helper methods - combines an array of delegates returning a real number or a vector into vector or matrix functions. The resulting vector function returns a vector whose components are the function values of the delegates in the array. var funcVector = FunctionFactory.RealFunctionsToVectorFunction(     new MultivariateRealFunction(myFunc1),     new MultivariateRealFunction(myFunc2));  The IterativeAlgorithm<T> abstract base class Iterative algorithms are common in numerical computing - a method is executed repeatedly until a certain condition is reached, approximating the result of a calculation with increasing accuracy until a certain threshold is reached. If the desired accuracy is achieved, the algorithm is said to converge. This base class is derived by many classes in the Extreme.Mathematics.EquationSolvers and Extreme.Mathematics.Optimization namespaces, as well as the ManagedIterativeAlgorithm class which contains a driver method that manages the iteration process.  The ConvergenceTest abstract base class This class is used to specify algorithm Termination , convergence and results - calculates an estimate for the error, and signals termination of the algorithm when the error is below a specified tolerance. Termination Criteria - specify the success condition as the difference between some quantity and its actual value is within a certain tolerance – 2 ways: absolute error - difference between the result and the actual value. relative error is the difference between the result and the actual value relative to the size of the result. Tolerance property - specify trade-off between accuracy and execution time. The lower the tolerance, the longer it will take for the algorithm to obtain a result within that tolerance. Most algorithms in the EO NumLib have a default value of MachineConstants.SqrtEpsilon - gives slightly less than 8 digits of accuracy. ConvergenceCriterion property - specify under what condition the algorithm is assumed to converge. Using the ConvergenceCriterion enum: WithinAbsoluteTolerance / WithinRelativeTolerance / WithinAnyTolerance / NumberOfIterations Active property - selectively ignore certain convergence tests Error property - returns the estimated error after a run MaxIterations / MaxEvaluations properties - Other Termination Criteria - If the algorithm cannot achieve the desired accuracy, the algorithm still has to end – according to an absolute boundary. Status property - indicates how the algorithm terminated - the AlgorithmStatus enum values:NoResult / Busy / Converged (ended normally - The desired accuracy has been achieved) / IterationLimitExceeded / EvaluationLimitExceeded / RoundOffError / BadFunction / Divergent / ConvergedToFalseSolution. After the iteration terminates, the Status should be inspected to verify that the algorithm terminated normally. Alternatively, you can set the ThrowExceptionOnFailure to true. Result property - returns the result of the algorithm. This property contains the best available estimate, even if the desired accuracy was not obtained. IterationsNeeded / EvaluationsNeeded properties - returns the number of iterations required to obtain the result, number of function evaluations.  Concrete Types of Convergence Test classes SimpleConvergenceTest class - test if a value is close to zero or very small compared to another value. VectorConvergenceTest class - test convergence of vectors. This class has two additional properties. The Norm property specifies which norm is to be used when calculating the size of the vector - the VectorConvergenceNorm enum values: EuclidianNorm / Maximum / SumOfAbsoluteValues. The ErrorMeasure property specifies how the error is to be measured – VectorConvergenceErrorMeasure enum values: Norm / Componentwise ConvergenceTestCollection class - represent a combination of tests. The Quantifier property is a ConvergenceTestQuantifier enum that specifies how the tests in the collection are to be combined: Any / All  The AlgorithmHelper Class inherits from IterativeAlgorithm<T> and exposes two methods for convergence testing. IsValueWithinTolerance<T> method - determines whether a value is close to another value to within an algorithm's requested tolerance. IsIntervalWithinTolerance<T> method - determines whether an interval is within an algorithm's requested tolerance.

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• Performance Improvement: Alternative for array_flip function.

  - by Rachel

  Is there any way I can avoid using array_flip to optimize performance. I am doing a select statement from database, preparing the query and executing it and storing data as an associative array in $resultCollection and than I have array op and for each element in $resultCollection am storing its outputId in op[] as evident from the code. I have explained code and so my question is how can I achieve an similar alternative for array_flip with using array_flip as I want to improve performance. $resultCollection = $statement->fetchAll(PDO::FETCH_ASSOC); $op = array(); //Looping through result collection and storing unicaOfferId into op array. foreach ($resultCollection as $output) { $op[] = $output['outputId']; } //Here op array has key as 0, 1, 2...and value as id {which I am interested in} //Flip op array to get unica offer ids as key $op = array_flip($op); //Doing a flip to get id as key. foreach ($ft as $Id => $Off) { $ft[$Id]['is_set'] = isset($op[$Id]); }

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• Doctrine_Table_Exception: Unknown relation alias shoesTable in /home/sadiqsof/public_html/projects/g

  - by Sadiqur Rahman

  I am getting following error message: Doctrine_Table_Exception: Unknown relation alias shoesTable in /home/sadiqsof/public_html/projects/giftshoes/system/database/doctrine/Doctrine/Relation/Parser.php on line 237 My Code is below: ------------BaseShoe------------ <?php // Connection Component Binding Doctrine_Manager::getInstance()->bindComponent('Shoes', 'sadiqsof_giftshoes'); /** * BaseShoes * * This class has been auto-generated by the Doctrine ORM Framework * * @property integer $sku * @property string $name * @property string $keywords * @property string $description * @property string $manufacturer * @property float $sale_price * @property float $price * @property string $url * @property string $image * @property string $category * @property Doctrine_Collection $Viewes * * @package ##PACKAGE## * @subpackage ##SUBPACKAGE## * @author ##NAME## <##EMAIL##> * @version SVN: $Id: Builder.php 6820 2009-11-30 17:27:49Z jwage $ */ abstract class BaseShoes extends Doctrine_Record { public function setTableDefinition() { $this->setTableName('shoes'); $this->hasColumn('sku', 'integer', 4, array( 'type' => 'integer', 'fixed' => 0, 'unsigned' => false, 'primary' => true, 'autoincrement' => false, 'length' => '4', )); $this->hasColumn('name', 'string', 255, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '255', )); $this->hasColumn('keywords', 'string', 255, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '255', )); $this->hasColumn('description', 'string', null, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('manufacturer', 'string', 20, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '20', )); $this->hasColumn('sale_price', 'float', null, array( 'type' => 'float', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('price', 'float', null, array( 'type' => 'float', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('url', 'string', null, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('image', 'string', null, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('category', 'string', 50, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '50', )); } public function setUp() { parent::setUp(); $this->hasMany('Viewes', array( 'local' => 'sku', 'foreign' => 'sku')); } } --------------ShoesTable-------- <?php class ShoesTable extends Doctrine_Table { function getAllShoes($from = 0, $total = 15) { $q = Doctrine_Query::create() ->from('Shoes') ->limit($total) ->offset($from); return $q->execute(array(), Doctrine::HYDRATE_ARRAY); } } ---------------Shoes Model----------------- <?php /** * Shoes * * This class has been auto-generated by the Doctrine ORM Framework * * @package ##PACKAGE## * @subpackage ##SUBPACKAGE## * @author ##NAME## <##EMAIL##> * @version SVN: $Id: Builder.php 6820 2009-11-30 17:27:49Z jwage $ */ class Shoes extends BaseShoes { function __construct() { parent::__construct(); $this->shoesTable = Doctrine::getTable('Shoes'); } function getAllShoes() { return $this->shoesTable->getAllShoes(); } }

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• Doctrine_Table_Exception: Unknown relation alias [closed]

  - by Sadiqur Rahman

  I am getting following error message: Doctrine_Table_Exception: Unknown relation alias shoesTable in /home/public_html/projects/giftshoes/system/database/doctrine/Doctrine/Relation/Parser.php on line 237 My Code is below: ------------BaseShoe------------ <?php // Connection Component Binding Doctrine_Manager::getInstance()->bindComponent('Shoes', 'sadiqsof_giftshoes'); /** * BaseShoes * * This class has been auto-generated by the Doctrine ORM Framework * * @property integer $sku * @property string $name * @property string $keywords * @property string $description * @property string $manufacturer * @property float $sale_price * @property float $price * @property string $url * @property string $image * @property string $category * @property Doctrine_Collection $Viewes * * @package ##PACKAGE## * @subpackage ##SUBPACKAGE## * @author ##NAME## <##EMAIL##> * @version SVN: $Id: Builder.php 6820 2009-11-30 17:27:49Z jwage $ */ abstract class BaseShoes extends Doctrine_Record { public function setTableDefinition() { $this->setTableName('shoes'); $this->hasColumn('sku', 'integer', 4, array( 'type' => 'integer', 'fixed' => 0, 'unsigned' => false, 'primary' => true, 'autoincrement' => false, 'length' => '4', )); $this->hasColumn('name', 'string', 255, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '255', )); $this->hasColumn('keywords', 'string', 255, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '255', )); $this->hasColumn('description', 'string', null, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('manufacturer', 'string', 20, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '20', )); $this->hasColumn('sale_price', 'float', null, array( 'type' => 'float', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('price', 'float', null, array( 'type' => 'float', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('url', 'string', null, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('image', 'string', null, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '', )); $this->hasColumn('category', 'string', 50, array( 'type' => 'string', 'fixed' => 0, 'unsigned' => false, 'primary' => false, 'notnull' => true, 'autoincrement' => false, 'length' => '50', )); } public function setUp() { parent::setUp(); $this->hasMany('Viewes', array( 'local' => 'sku', 'foreign' => 'sku')); } } --------------ShoesTable-------- <?php class ShoesTable extends Doctrine_Table { function getAllShoes($from = 0, $total = 15) { $q = Doctrine_Query::create() ->from('Shoes') ->limit($total) ->offset($from); return $q->execute(array(), Doctrine::HYDRATE_ARRAY); } } ---------------Shoes Model----------------- <?php /** * Shoes * * This class has been auto-generated by the Doctrine ORM Framework * * @package ##PACKAGE## * @subpackage ##SUBPACKAGE## * @author ##NAME## <##EMAIL##> * @version SVN: $Id: Builder.php 6820 2009-11-30 17:27:49Z jwage $ */ class Shoes extends BaseShoes { function __construct() { parent::__construct(); $this->shoesTable = Doctrine::getTable('Shoes'); } function getAllShoes() { return $this->shoesTable->getAllShoes(); } }

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• PHP Dynamic Breadcrumb, small modification

  - by Adrian M.

  Hello, I got this code from someone and it works very well, I just want to remove the link from the last element of the array: //get rid of empty parts $crumbs = array_filter($crumbs); $result = array(); $path = ''; foreach($crumbs as $crumb){ $path .= '/' . $crumb; $name = ucfirst(str_replace(array(".php","_"),array(""," "), $crumb)); $result[] = "<a href=\"$path\">$name</a>"; } print implode(' > ', $result); This will output for example: Content Common File I just want a to remove the link from the last item - "File" to be just plain text.. I tried myself to count the array items and then if the array item is the last one then to print as plain text the last item.. but I'm still noob, I haven't managed to get a proper result.. Thank you!

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• how can i change the colourindex of a word in a string for msword using Win32:OLE

  - by lokesh

  hi all, i am actually trying to change the color index for the first word with braces in an array, for eg if i have an array like this... @array=" (Love) is (beautiful), Its like an (air), So it can be (only) felt, (Cannot) be (seen)." and i need the colour of the first word that are inside the braces () ie "(Love), (Cannot)" including () to be in RED and rest of the contents in BLACK and print the entire contents of the array in msword(2003) using win32::ole....and am using windows xp.This array is just an example the contents of an array will change but first word with braces has to be printed in red can any one help me pls... its very urgent...Thanks a lot to all who help me in this regard.

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• Pass associative arrays in call_user_func_array(...)

  - by Matt

  Hey all, I'm building a templating system and I'm running in to an issue with calling functions on the fly. When I try the following: $args = array( 4, 'test' => 'hello', 'hi' ); You know.. some numerical elements some associative elements, call_user_func_array($function, $args); converts the array to something like this: $args = array( 4, 'hello', 'hi' ); Is there any way around this other than passing an array like this: $args = array( 4, array('test' => 'hello'), 'hi' ); Thanks! Matt

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• glColor3f Setting colour

  - by Aaron

  This draws a white vertical line from 640 to 768 at x512: glDisable(GL_TEXTURE_2D); glBegin(GL_LINES); glColor3f((double)R/255,(double)G/255,(double)B/255); glVertex3f(SX, -SPosY, 0); // origin of the line glVertex3f(SX, -EPosY, 0); // ending point of the line glEnd(); glEnable(GL_TEXTURE_2D); This works, but after having a problem where it wouldn't draw it white (Or to any colour passed) I discovered that disabling GL_TEXTURE_2D Before drawing the line, and the re-enabling it afterwards for other things, fixed it. I want to know, is this a normal step a programmer might take? Or is it highly inefficient? I don't want to be causing any slow downs due to a mistake =) Thanks

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• Formating a text in a table cell with PHPWord e.g. bold, font, size e.t.c

  - by alphy

  I have the code snippet below //create a new word document $word= new PHPWord(); //create potrait orientation $section=$word->createSection(); $table = $section->addTable(); $word->addFontStyle('rStyle', array('bold'=>true, 'italic'=>true, 'size'=>16)); //header row $table->addRow(400, array('bgColor'=>'dbdbdb')); $table->addCell(2000, array('bgColor'=>'dbdbdb'))->addText('Cell 1','rStyle'); $table->addCell(3500, array('bgColor'=>'dbdbdb'))->addText('Cell 1'); $table->addCell(1500, array('bgColor'=>'dbdbdb'))->addText('Cell 1','rStyle'); $table->addCell(2000, array('bgColor'=>'dbdbdb'))->addText('Cell 1'); // Save File $objWriter = PHPWord_IOFactory::createWriter($word, 'Word2007'); $objWriter->save('Text.docx'); echo 'Text.docx created successfully'; } How can i add text formatting to a cell value to bold, italic, font-size etc, I have tried as shown above but it does not work

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