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  • Floating point precision nuances.

    - by user247077
    Hi, I found this code in NVIDIA's cuda SDK samples. void computeGold( float* reference, float* idata, const unsigned int len) { reference[0] = 0; double total_sum = 0; unsigned int i; for( i = 1; i < len; ++i) { total_sum += idata[i-1]; reference[i] = idata[i-1] + reference[i-1]; } // Here it should be okay to use != because we have integer values // in a range where float can be exactly represented if (total_sum != reference[i-1]) printf("Warning: exceeding single-precision accuracy. Scan will be inaccurate.\n"); } (C) Nvidia Corp Can somebody please tell me a case where the warning would be printed, and most importantly, why. Thank you very much.

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  • Thread feeding other MultiThreading

    - by alaamh
    I see it's easy to open pipe between two process using fork, but how we can passing open pipe to threads. Assume we need to pass out of PROGRAM A to PROGRAM B "may by more than one thread", PROGRAM B send his output to PROGRAM C #include <stdio.h> #include <stdlib.h> #include <pthread.h> struct targ_s { char* reader; }; void *thread1(void *arg) { struct targ_s *targ = (struct targ_s*) arg; int status, fd[2]; pid_t pid; pipe(fd); pid = fork(); if (pid == 0) { int fd = fileno( targ->fd_reader ); dup2(STDIN_FILENO, fd); close(fd[0]); dup2(fd[1], STDOUT_FILENO); close(fd[1]); execvp ("PROGRAM B", NULL); exit(1); } else { close(fd[1]); dup2(fd[0], STDIN_FILENO); close(fd[0]); execl("PROGRAM C", NULL); wait(&status); return NULL; } } int main(void) { FILE *fpipe; char *command = "PROGRAM A"; char buffer[1024]; if (!(fpipe = (FILE*) popen(command, "r"))) { perror("Problems with pipe"); exit(1); } char* outfile = "out.dat"; FILE* f = fopen (outfile, "wb"); int fd = fileno( f ); struct targ_s targ; targ.fd_reader = outfile; pthread_t thid; if (pthread_create(&thid, NULL, thread1, &targ) != 0) { perror("pthread_create() error"); exit(1); } int len; while (read(fpipe, buffer, sizeof (buffer)) != 0) { len = strlen(buffer); write(fd, buffer, len); } pclose(fpipe); return (0); }

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  • improve my python program to fetch the desire rows by using if condition

    - by user2560507
    unique.txt file contains: 2 columns with columns separated by tab. total.txt file contains: 3 columns each column separated by tab. I take each row from unique.txt file and find that in total.txt file. If present then extract entire row from total.txt and save it in new output file. ###Total.txt column a column b column c interaction1 mitochondria_205000_225000 mitochondria_195000_215000 interaction2 mitochondria_345000_365000 mitochondria_335000_355000 interaction3 mitochondria_345000_365000 mitochondria_5000_25000 interaction4 chloroplast_115000_128207 chloroplast_35000_55000 interaction5 chloroplast_115000_128207 chloroplast_15000_35000 interaction15 2_10515000_10535000 2_10505000_10525000 ###Unique.txt column a column b mitochondria_205000_225000 mitochondria_195000_215000 mitochondria_345000_365000 mitochondria_335000_355000 mitochondria_345000_365000 mitochondria_5000_25000 chloroplast_115000_128207 chloroplast_35000_55000 chloroplast_115000_128207 chloroplast_15000_35000 mitochondria_185000_205000 mitochondria_25000_45000 2_16595000_16615000 2_16585000_16605000 4_2785000_2805000 4_2775000_2795000 4_11395000_11415000 4_11385000_11405000 4_2875000_2895000 4_2865000_2885000 4_13745000_13765000 4_13735000_13755000 My program: file=open('total.txt') file2 = open('unique.txt') all_content=file.readlines() all_content2=file2.readlines() store_id_lines = [] ff = open('match.dat', 'w') for i in range(len(all_content)): line=all_content[i].split('\t') seq=line[1]+'\t'+line[2] for j in range(len(all_content2)): if all_content2[j]==seq: ff.write(seq) break Problem: but istide of giving desire output (values of those 1st column that fulfile the if condition). i nead somthing like if jth of unique.txt == ith of total.txt then write ith row of total.txt into new file.

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  • Convert Military time to string representation

    - by RRUZ
    I have an column declarated as int (called HourMil) wich store the time in military format. i need convert this values to an formated string (HH:MM) example HourMil = 710 -> must be 07:10 HourMil = 1305 -> must be 13:05 Actually i am using this code (and works ok) for convert the column HourMil to the string representation. SELECT SUBSTRING(LEFT('0',4-LEN(CAST(HourMil AS VARCHAR)))+CAST(HourMil AS VARCHAR),1,2)+':'+SUBSTRING(LEFT('0',4-LEN(CAST(HourMil AS VARCHAR)))+CAST(HourMil AS VARCHAR),3,2) FROM MYTABLE but I think this code can be improved.

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  • better for-loop syntax for detecting empty sequences?

    - by Dmitry Beransky
    Hi, Is there a better way to write the following: row_counter = 0 for item in iterable_sequence: # do stuff with the item counter += 1 if not row_counter: # handle the empty-sequence-case Please keep in mind that I can't use len(iterable_sequence) because 1) not all sequences have known lengths; 2) in some cases calling len() may trigger loading of the sequence's items into memory (as the case would be with sql query results). The reason I ask is that I'm simply curious if there is a way to make above more concise and idiomatic. What I'm looking for is along the lines of: for item in sequence: #process item *else*: #handle the empty sequence case (assuming "else" here worked only on empty sequences, which I know it doesn't)

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  • subplot matplotlib wrong syntax

    - by madptr
    I am using matplotlib to subplot in a loop. For instance, i would like to subplot 49 data sets, and from the doc, i implemented it this way; import numpy as np import matplotlib.pyplot as plt X1=list(range(0,10000,1)) X1 = [ x/float(10) for x in X1 ] nb_mix = 2 parameters = [] for i in range(49): param = [] Y = [0] * len(X1) for j in range(nb_mix): mean = 5* (1 + (np.random.rand() * 2 - 1 ) * 0.5 ) var = 10* (1 + np.random.rand() * 2 - 1 ) scale = 5* ( 1 + (np.random.rand() * 2 - 1) * 0.5 ) Y = [ Y[k] + scale * np.exp(-((X1[k] - mean)/float(var))**2) for k in range(len(X1)) ] param = param + [[mean, var, scale]] ax = plt.subplot(7, 7, i + 1) ax.plot(X1, Y) parameters = parameters + [param] ax.show() However, i have an index out of range error from i=0 onwards. Where can i do better to have it works ? Thanks

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  • Linked lists in Java - Help with writing methods

    - by user368241
    Representation of a string in linked lists In every intersection in the list there will be 3 fields : The letter itself. The number of times it appears consecutively. A pointer to the next intersection in the list. The following class CharNode represents a intersection in the list : public class CharNode { private char _data; private int _value; private charNode _next; public CharNode (char c, int val, charNode n) { _data = c; _value = val; _next = n; } public charNode getNext() { return _next; } public void setNext (charNode node) { _next = node; } public int getValue() { return _value; } public void setValue (int v) { value = v; } public char getData() { return _data; } public void setData (char c) { _data = c; } } The class StringList represents the whole list : public class StringList { private charNode _head; public StringList() { _head = null; } public StringList (CharNode node) { _head = node; } } Add methods to the class StringList according to the details : (I will add methods gradually according to my specific questions) (Pay attention, these are methods from the class String and we want to fulfill them by the representation of a string by a list as explained above) Pay attention to all the possible error cases. Write what is the time complexity and space complexity of every method that you wrote. Make sure the methods you wrote are effective. It is NOT allowed to use ready classes of Java. It is NOT allowed to move to string and use string operations. 1) public int indexOf (int ch) - returns the index in the string it is operated on of the first appeareance of the char "ch". If the char "ch" doesn't appear in the string, returns -1. If the value of fromIndex isn't in the range, returns -1. Here is my try : public int indexOf (int ch) { int count = 0; charNode pos = _head; if (pos == null ) { return -1; } for (pos = _head; pos!=null && pos.getData()!=ch; pos = pos.getNext()) { count = count + pos.getValue(); } if (pos==null) return -1; return count; } Time complexity = O(N) Space complexity = O(1) EDIT : I have a problem. I tested it in BlueJ and if the char ch doesn't appear it returns -1 but if it does, it always returns 0 and I don't understand why... I am confused. How can the compiler know that the value is the number of times the letter appears consecutively? Can I assume this because its given on the question or what? If it's true and I can assume this, then my code should be correct right? Ok I just spoke with my instructor and she said it isn't required to write it in the exercise but in order for me to test that it indeed works, I need to open a new class and write a code for making a list so that the the value of every node is the number of times the letter appears consecutively. Can someone please assist me? So I will copy+paste to BlueJ and this way I will be able to test all the methods. Meanwhile I am moving on to the next methods. 2) public int indexOf (int ch, int fromIndex) - returns the index in the string it is operated on of the first appeareance of the char "ch", as the search begins in the index "fromIndex". If the char "ch" doesn't appear in the string, returns -1. If the value of fromIndex doesn't appear in the range, returns -1. Here is my try: public int indexOf (int ch, int fromIndex) { int count = 0, len=0, i; charNode pos = _head; CharNode cur = _head; for (pos = _head; pos!=null; pos = pos.getNext()) { len = len+1; } if (fromIndex<0 || fromIndex>=len) return -1; for (i=0; i<fromIndex; i++) { cur = cur.getNext(); } if (cur == null ) { return -1; } for (cur = _head; cur!=null && cur.getData()!=ch; cur = cur.getNext()) { count = count + cur.getValue(); } if (cur==null) return -1; return count; } Time complexity = O(N) ? Space complexity = O(1) 3) public StringList concat (String str) - returns a string that consists of the string that it is operated on and in its end the string "str" is concatenated. Here is my try : public StringList concat (String str) { String str = ""; charNode pos = _head; if (str == null) return -1; for (pos = _head; pos!=null; pos = pos.getNext()) { str = str + pos.getData(); } str = str + "str"; return str; } Time complexity = O(N) Space complexity = O(1)

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  • How can CopyOnWriteArrayList be thread-safe?

    - by Shooshpanchick
    I've taken a look into OpenJDK's sources of CopyOnWriteArrayList and it seems that all write operations are protected by the same lock and read operations are not protected at all. As I understand, under JMM all accesses to a variable (both read and write) should be protected by lock or reordering effects may occur. For example, set(int, E) method contains these lines (under lock): /* 1 */ int len = elements.length; /* 2 */ Object[] newElements = Arrays.copyOf(elements, len); /* 3 */ newElements[index] = element; /* 4 */ setArray(newElements); The get(int) method, on the other hand, only does return get(getArray(), index);. In my understanding of JMM, this means that get may observe the array in an inconsistent state if statements 1-4 are reordered like 1-2(new)-4-2(copyOf)-3. Do I understand JMM incorrectly or is there any other explanations on why CopyOnWriteArrayList is thread-safe?

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  • Writing an optimised and efficient search engine with mySQL and ColdFusion

    - by Mel
    I have a search page with the following scenarios listed below. I was told there was a better way to do it, but not how, and that I am using too many if statements, and that it's prone to causing an error through url manipulation: Search.cfm will processes a search made from a search bar present on all pages, with one search input (titleName). If search.cfm is accessed manually (through URL not through using the simple search bar on all pages) it displays an advanced search form with three inputs (titleName, genreID, platformID) or it evaluates searchResponse variable and decides what to do. If simple search query is blank, has no results, or less than 3 characters it displays an error If advanced search query is blank, has no results, or less than 3 characters it displays an error If any successful search returns results, they come back normally. The top-of-page logic is as follows: <!---SET DEFAULT VARIABLE---> <cfparam name="variables.searchResponse" default=""> <!---CHECK TO SEE IF SIMPLE SEARCH A FORM WAS SUBMITTED AND EXECUTE SEARCH IF IT WAS---> <cfif IsDefined("Form.simpleSearch") AND Len(Trim(Form.titleName)) LTE 2> <cfset variables.searchResponse = "invalidString"> <cfelseif IsDefined("Form.simpleSearch") AND Len(Trim(Form.titleName)) GTE 3> <!---EXECUTE METHOD AND GET DATA---> <cfinvoke component="myComponent" method="simpleSearch" searchString="#Form.titleName#" returnvariable="simpleSearchResult"> <cfset variables.searchResponse = "simpleSearchResult"> </cfif> <!---CHECK IF ANY RECORDS WERE FOUND---> <cfif IsDefined("variables.simpleSearchResult") AND simpleSearchResult.RecordCount IS 0> <cfset variables.searchResponse = "noResult"> </cfif> <!---CHECK IF ADVANCED SEARCH FORM WAS SUBMITTED---> <cfif IsDefined("Form.AdvancedSearch") AND Len(Trim(Form.titleName)) LTE 2> <cfset variables.searchResponse = "invalidString"> <cfelseif IsDefined("Form.advancedSearch") AND Len(Trim(Form.titleName)) GTE 2> <!---EXECUTE METHOD AND GET DATA---> <cfinvoke component="myComponent" method="advancedSearch" returnvariable="advancedSearchResult" titleName="#Form.titleName#" genreID="#Form.genreID#" platformID="#Form.platformID#"> <cfset variables.searchResponse = "advancedSearchResult"> </cfif> <!---CHECK IF ANY RECORDS WERE FOUND---> <cfif IsDefined("variables.advancedSearchResult") AND advancedSearchResult.RecordCount IS 0> <cfset variables.searchResponse = "noResult"> </cfif> I'm using the searchResponse variable to decide what the the page displays, based on the following scenarios: <!---ALWAYS DISPLAY SIMPLE SEARCH BAR AS IT'S PART OF THE HEADER---> <form name="simpleSearch" action="search.cfm" method="post"> <input type="hidden" name="simpleSearch" /> <input type="text" name="titleName" /> <input type="button" value="Search" onclick="form.submit()" /> </form> <!---IF NO SEARCH WAS SUBMITTED DISPLAY DEFAULT FORM---> <cfif searchResponse IS ""> <h1>Advanced Search</h1> <!---DISPLAY FORM---> <form name="advancedSearch" action="search.cfm" method="post"> <input type="hidden" name="advancedSearch" /> <input type="text" name="titleName" /> <input type="text" name="genreID" /> <input type="text" name="platformID" /> <input type="button" value="Search" onclick="form.submit()" /> </form> </cfif> <!---IF SEARCH IS BLANK OR LESS THAN 3 CHARACTERS DISPLAY ERROR MESSAGE---> <cfif searchResponse IS "invalidString"> <cfoutput> <h1>INVALID SEARCH</h1> </cfoutput> </cfif> <!---IF SEARCH WAS MADE BUT NO RESULTS WERE FOUND---> <cfif searchResponse IS "noResult"> <cfoutput> <h1>NO RESULT FOUND</h1> </cfoutput> </cfif> <!---IF SIMPLE SEARCH WAS MADE A RESULT WAS FOUND---> <cfif searchResponse IS "simpleSearchResult"> <cfoutput> <h1>Search Results</h1> </cfoutput> <cfoutput query="simpleSearchResult"> <!---DISPLAY QUERY DATA---> </cfoutput> </cfif> <!---IF ADVANCED SEARCH WAS MADE A RESULT WAS FOUND---> <cfif searchResponse IS "advancedSearchResult"> <cfoutput> <h1>Search Results</h1> <p>Your search for "#Form.titleName#" returned #advancedSearchResult.RecordCount# result(s).</p> </cfoutput> <cfoutput query="advancedSearchResult"> <!---DISPLAY QUERY DATA---> </cfoutput> </cfif> Is my logic a) not efficient because my if statements/is there a better way to do this? And b) Can you see any scenarios where my code can break? I've tested it but I have not been able to find any issues with it. And I have no way of measuring performance. Any thoughts and ideas would be greatly appreciated. Many thanks

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  • How can I convert a decimal to a fraction ?

    - by CornyD
    How do I convert a indefinite decimal (i.e. .333333333...) to a string fraction representation (i.e. "1/3"). I am using VBA and the following is the code I used (i get an overflow error at the line "b = a Mod b": Function GetFraction(ByVal Num As Double) As String If Num = 0# Then GetFraction = "None" Else Dim WholeNumber As Integer Dim DecimalNumber As Double Dim Numerator As Double Dim Denomenator As Double Dim a, b, t As Double WholeNumber = Fix(Num) DecimalNumber = Num - Fix(Num) Numerator = DecimalNumber * 10 ^ (Len(CStr(DecimalNumber)) - 2) Denomenator = 10 ^ (Len(CStr(DecimalNumber)) - 2) If Numerator = 0 Then GetFraction = WholeNumber Else a = Numerator b = Denomenator t = 0 While b <> 0 t = b b = a Mod b a = t Wend If WholeNumber = 0 Then GetFraction = CStr(Numerator / a) & "/" & CStr(Denomenator / a) Else GetFraction = CStr(WholeNumber) & " " & CStr(Numerator / a) & "/" & CStr(Denomenator / a) End If End If End If End Function

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  • Permutations in python 2.5.2

    - by flpgdt
    Hi, I have a list of numbers for input, e.g. 671.00 1,636.00 436.00 9,224.00 and I want to generate all possible sums with a way to id it for output, e.g.: 671.00 + 1,636.00 = 2,307.00 671.00 + 436.00 = 1,107.00 671.00 + 9,224.00 = 9,224.00 671.00 + 1,636.00 + 436.00 = 2,743.00 ... and I would like to do it in Python My current constrains are: a) I'm just learning python now (that's part of the idea) b) I will have to use Python 2.5.2 (no intertools) I think I have found a piece of code that may help: def all_perms(str): if len(str) <=1: yield str else: for perm in all_perms(str[1:]): for i in range(len(perm)+1): #nb str[0:1] works in both string and list contexts yield perm[:i] + str[0:1] + perm[i:] ( from these guys ) But I'm not sure how to use it in my propose. Could someone trow some tips and pieces of code of help? cheers, f.

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  • Override tablesorter CSS

    - by user1712810
    I am using jquery tablesorter. When the page loads, I have a code to highlight the background color of certain rows in the table. Since tablesorter is used I guess it overrides the css and not allowing to change the background color of the rows. This is the code. This function automatically loads when the page gets loaded. I removed table-sorter to the table and tried this. It works. I have to get it to work with the table-sorter applied. $(document).ready(function() { var row, len, results; row = 0; results = []; while (row < len) { if ($("#tab1 #example_"+row+"chkbx").is(":checked")) { $("#tab1 #example_" + row).css("background-color", "#c6b79f"); } row++; } return results; });

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  • Diagonal Output of Assembly programe

    - by Yousuf Umar
    i have this assembly programe and i want to diagonal ouptut of this programe but i dont know how to put tabspace in assembly section .text global _start ;must be declared for using gcc _start: ;tell linker entry point mov edx, len ;message length mov ecx, msg ;message to write mov ebx, 1 ;file descriptor (stdout) mov eax, 4 ;system call number (sys_write) int 0x80 ;call kernel mov eax, 1 ;system call number (sys_exit) int 0x80 ;call kernel section .data msg db 'Y',10,'O',10,'U',10,'S',10,'U',10,'F' ;our dear string len equ $ - msg ;length of our dear string output of my programe is Y O U S U F output shoud like this Y O U S U F or is there any other way to write this programe and get this output

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  • Udp server sending only 0 bytes of data

    - by mawia
    Hi all, This is a simple Udp server.I am trying to transmit data to some clients,but unfortunetly it is unable to transmit data.Though send is running quite successfully but it is returning with a return value meaning it has send nothing.On the client they are receiving but again obviously,zero bytes. void* UdpServerStreamToClients(void *fileToServe) { int sockfd,n=0,k; struct sockaddr_in servaddr,cliaddr; socklen_t len; char dataToSend[1000]; sockfd=socket(AF_INET,SOCK_DGRAM,0); bzero(&servaddr,sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_addr.s_addr=htonl(INADDR_ANY); servaddr.sin_port=htons(32000); bind(sockfd,(struct sockaddr *)&servaddr,sizeof(servaddr)); FILE *fp; if((fp=fopen((char*)fileToServe,"r"))==NULL) { printf("can not open file "); perror("fopen"); exit(1); } int dataRead=1; while(dataRead) { len = sizeof(cliaddr); if((dataRead=fread(dataToSend,1,500,fp))<0) { perror("fread"); exit(1); } //sleep(2); for(list<clientInfo>::iterator it=clients.begin();it!=clients.end();it++) { cliaddr.sin_family = AF_INET; inet_aton(inet_ntoa(it->addr.sin_addr),&cliaddr.sin_addr); cliaddr.sin_port = htons(it->udp_port); n=sendto(sockfd,dataToSend,sizeof(dataToSend),0,(struct sockaddr *)&cliaddr,len); cout<<"number of bytes send by udp: "<< n << endl; printf("SEND this message %d : %s to %s :%d \n",n,dataToSend,inet_ntoa(cliaddr.sin_addr), ntohs(cliaddr.sin_port)); } } } I am checking the value of sizeof(dataTosend) and it is pretty much as expected ie thousand ie the size of buffer. Are you people seeing some possible flaw in it. All of the help in this regard will be appreciated. Thanks!

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  • Is it faster to loop through a Python set of number or a set of letters?

    - by Scott Bartell
    Is it faster to loop through a Python set of numbers or a Python set of letters given that each set is the exact same length and each item within each set is the same length? Why? I would think that there would be a difference because letters have more possible characters [a-zA-Z] than numbers [0-9] and therefor would be more 'random' and likely affect the hashing to some extent. numbers = set([00000,00001,00002,00003,00004,00005, ... 99999]) letters = set(['aaaaa','aaaab','aaaac','aaaad', ... 'aaabZZ']) # this is just an example, it does not actually end here for item in numbers: do_something() for item in letters: do_something() where len(numbers) == len(letters) Update: I am interested in Python's specific hashing algorithm and what happens behind the scenes with this implementation.

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  • python [lxml] - cleaning out html tags

    - by sadhu_
    from lxml.html.clean import clean_html, Cleaner def clean(text): try: cleaner = Cleaner(scripts=True, embedded=True, meta=True, page_structure=True, links=True, style=True, remove_tags = ['a', 'li', 'td']) print (len(cleaner.clean_html(text))- len(text)) return cleaner.clean_html(text) except: print 'Error in clean_html' print sys.exc_info() return text I put together the above (ugly) code as my initial forays into python land. I'm trying to use lxml cleaner to clean out a couple of html pages, so in the end i am just left with the text and nothing else - but try as i might, the above doesnt appear to work as such, i'm still left with a substial amount of markup (and it doesnt appear to be broken html), and particularly links, which aren't getting removed, despite the args i use in remove_tags and links=True any idea whats going on, perhaps im barking up the wrong tree with lxml ? i thought this was the way to go with html parsing in python?

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  • Check if key exists in $_SESSION by building index string

    - by Kim
    I need to check if a key exists and return its value if it does. Key can be an array with subkeys or endkey with a value. $_SESSION['mainKey']['testkey'] = 'value'; var_dump(doesKeyExist('testkey')); function doesKeyExist($where) { $parts = explode('/',$where); $str = ''; for($i = 0,$len = count($parts);$i<$len;$i++) { $str .= '[\''. $parts[$i] .'\']'; } $keycheck = '$_SESSION[\'mainKey\']' . $str; if (isset(${$keycheck})) { return ${$keycheck}; } // isset($keycheck) = true, as its non-empty. actual content is not checked // isset(${$keycheck}) = false, but should be true. ${$var} forces a evaluate content // isset($_SESSION['mainKey']['testkey']) = true } What am I doing wrong ? Using PHP 5.3.3.

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  • How to interpret situations where Math.Acos() reports invalid input?

    - by Sean Ochoa
    Hey all. I'm computing the angle between two vectors, and sometimes Math.Acos() returns NaN when it's input is out of bounds (-1 input && input 1) for a cosine. What does that mean, exactly? Would someone be able to explain what's happening? Any help is appreciated! Here's me method: public double AngleBetween(vector b) { var dotProd = this.Dot(b); var lenProd = this.Len*b.Len; var divOperation = dotProd/lenProd; // http://msdn.microsoft.com/en-us/library/system.math.acos.aspx return Math.Acos(divOperation) * (180.0 / Math.PI); }

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  • crc24 from c to python

    - by biiiiiaw
    can someone please translate this code to python? i have tried and tried again, but have not managed it: #define CRC24_INIT 0xB704CEL #define CRC24_POLY 0x1864CFBL typedef long crc24; crc24 crc_octets(unsigned char *octets, size_t len) { crc24 crc = CRC24_INIT; int i; while (len--) { crc ^= (*octets++) << 16; for (i = 0; i < 8; i++) { crc <<= 1; if (crc & 0x1000000) crc ^= CRC24_POLY; } } return crc & 0xFFFFFFL; } i have the rotate left function (ROL24(value,bits_to_rotate_by)), which i know works since i got it from a source code of a reputable programmer, but i dont get the * and ++ on octet. i only sort of understand how ++ works in c++, and i dont know what * is at all

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  • Finding a Eulerian Tour

    - by user590903
    I am trying to solve a problem on Udacity described as follows: # Find Eulerian Tour # # Write a function that takes in a graph # represented as a list of tuples # and return a list of nodes that # you would follow on an Eulerian Tour # # For example, if the input graph was # [(1, 2), (2, 3), (3, 1)] # A possible Eulerian tour would be [1, 2, 3, 1] I came up with the following solution, which, while not as elegant as some of the recursive algorithms, does seem to work within my test case. def find_eulerian_tour(graph): tour = [] start_vertex = graph[0][0] tour.append(start_vertex) while len(graph) > 0: current_vertex = tour[len(tour) - 1] for edge in graph: if current_vertex in edge: if edge[0] == current_vertex: current_vertex = edge[1] else: current_vertex = edge[0] graph.remove(edge) tour.append(current_vertex) break return tour graph = [(1, 2), (2, 3), (3, 1)] print find_eulerian_tour(graph) >> [1, 2, 3, 1] However, when submitting this, I get rejected by the grader. I am doing something wrong? I can't see any errors.

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  • VB6 debugging- doesn't go to error handling code.

    - by Can Ho
    Hi, I'm maintaining a vb6 project(ActiveX DLL). When debugging, the app run into the following function: Public Function HasValue(ByVal vValue) As Boolean On Error GoTo Err If IsMissing(vValue) Then HasValue = False ElseIf IsNull(vValue) Or Len(vValue) = 0 Then HasValue = False ElseIf isEmpty(vValue) Then HasValue = False Else HasValue = True End If Exit Function Err: If IsArray(vValue) Or IsObject(vValue) Then HasValue = True Else HasValue = False End If End Function and it stops at the line ElseIf IsNull(vValue) Or Len(vValue) = 0 Then vValue is a custom object, contains some properties(obviously, not null). Although I didn't put any break point there, the app stopped there and alerted error dialog saying that "Run-time error '438': Object doesn't support this property or method". We had error handling code but the app didn't run to error handling code. It just stopped at the line causing the error and I had to stop the application. Do you have any idea about that? Thank you very much.

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  • Removing items from a nested list Python

    - by johntfoster
    I'm trying to remove items from a nested list in Python. I have a nested list as follows: families = [[0, 1, 2],[0, 1, 2, 3],[0, 1, 2, 3, 4],[1, 2, 3, 4, 5],[2, 3, 4, 5, 6]] I want to remove the entries in each sublist that coorespond to the indexed position of the sublist in the master list. So, for example, I need to remove 0 from the first sublist, 1 from second sublist, etc. I am trying to use a list comrehension do do this. This is what I have tried: familiesNew = [ [ families[i][j] for j in families[i] if i !=j ] for i in range(len(families)) ] This works for range(len(families)) up to 3, however beyond that I get IndexError: list index out of range. I'm not sure why. Can somebody give me an idea of how to do this. Preferably a one-liner (list comprehension). Thanks.

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  • How to do elif statments more elegantly if appending to array in python

    - by user1741339
    I am trying to do a more elegant version of this code. This just basically appends a string to categorynumber depending on the number. Would appreciate any help. number = [100,150,200,500] categoryNumber = [] for i in range (0,len(number)): if (number [i] >=1000): categoryNumber.append('number > 1000') elif (number [i] >=200): categoryNumber.append('200 < number < 300') elif (number [i] >=100): categoryNumber.append('100 < number < 200') elif (number [i] >=50): categoryNumber.append('50 < number < 100') elif (number [i] < 50): categoryNumber.append('number < 50') for i in range(0,len(categoryNumber)): print i

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  • Cron job execute backup.bash

    - by leejava
    Dear all, I wish to let cron executes backup.bash, but when I try to create cron as below: */1 * * * * /var/www/mango_gis/delete_snapshot.bash /dev/null It didn't execute my script at all. Here is my script as below: #!/bin/bash get() { local pos=$1 shift eval 'echo ${'$pos'}'; } length(){ echo $#; } find_snapshots() { echo $(ec2-describe-snapshots | xargs -n1 basename); } snapshots=$(find_snapshots) len=$(length $snapshots) row_count=$(($len/6)) if(($row_count 6)); then delete_count=$(($row_count-6)) for (( i=1; i<=$delete_count; i++ )); do ec2-delete-snapshot $(echo $(get $((2+$((6*$(($i-1)))))) $snapshots)) /dev/null done fi Please advise... Leakhina

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  • Python 3 order of testing undetermined

    - by user578598
    string='a' p=0 while (p <len(string)) & (string[p]!='c') : p +=1 print ('the end but the process already died ') while (p <1) & (string[p]!='c') : IndexError: string index out of range I want to test a condition up to the end of a string (example string length=1) why are both parts of the and executed is the condition is already false! as long as p < len(string). the second part does not even need executing. if it does a lot of performance can be lost

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