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• NET Math Libraries

  - by JoshReuben

  NET Mathematical Libraries   .NET Builder for Matlab The MathWorks Inc. - http://www.mathworks.com/products/netbuilder/ MATLAB Builder NE generates MATLAB based .NET and COM components royalty-free deployment creates the components by encrypting MATLAB functions and generating either a .NET or COM wrapper around them. .NET/Link for Mathematica www.wolfram.com a product that 2-way integrates Mathematica and Microsoft's .NET platform call .NET from Mathematica - use arbitrary .NET types directly from the Mathematica language. use and control the Mathematica kernel from a .NET program. turns Mathematica into a scripting shell to leverage the computational services of Mathematica. write custom front ends for Mathematica or use Mathematica as a computational engine for another program comes with full source code. Leverages MathLink - a Wolfram Research's protocol for sending data and commands back and forth between Mathematica and other programs. .NET/Link abstracts the low-level details of the MathLink C API. Extreme Optimization http://www.extremeoptimization.com/ a collection of general-purpose mathematical and statistical classes built for the.NET framework. It combines a math library, a vector and matrix library, and a statistics library in one package. download the trial of version 4.0 to try it out. Multi-core ready - Full support for Task Parallel Library features including cancellation. Broad base of algorithms covering a wide range of numerical techniques, including: linear algebra (BLAS and LAPACK routines), numerical analysis (integration and differentiation), equation solvers. Mathematics leverages parallelism using .NET 4.0's Task Parallel Library. Basic math: Complex numbers, 'special functions' like Gamma and Bessel functions, numerical differentiation. Solving equations: Solve equations in one variable, or solve systems of linear or nonlinear equations. Curve fitting: Linear and nonlinear curve fitting, cubic splines, polynomials, orthogonal polynomials. Optimization: find the minimum or maximum of a function in one or more variables, linear programming and mixed integer programming. Numerical integration: Compute integrals over finite or infinite intervals, over 2D and higher dimensional regions. Integrate systems of ordinary differential equations (ODE's). Fast Fourier Transforms: 1D and 2D FFT's using managed or fast native code (32 and 64 bit) BigInteger, BigRational, and BigFloat: Perform operations with arbitrary precision. Vector and Matrix Library Real and complex vectors and matrices. Single and double precision for elements. Structured matrix types: including triangular, symmetrical and band matrices. Sparse matrices. Matrix factorizations: LU decomposition, QR decomposition, singular value decomposition, Cholesky decomposition, eigenvalue decomposition. Portability and performance: Calculations can be done in 100% managed code, or in hand-optimized processor-specific native code (32 and 64 bit). Statistics Data manipulation: Sort and filter data, process missing values, remove outliers, etc. Supports .NET data binding. Statistical Models: Simple, multiple, nonlinear, logistic, Poisson regression. Generalized Linear Models. One and two-way ANOVA. Hypothesis Tests: 12 14 hypothesis tests, including the z-test, t-test, F-test, runs test, and more advanced tests, such as the Anderson-Darling test for normality, one and two-sample Kolmogorov-Smirnov test, and Levene's test for homogeneity of variances. Multivariate Statistics: K-means cluster analysis, hierarchical cluster analysis, principal component analysis (PCA), multivariate probability distributions. Statistical Distributions: 25 29 continuous and discrete statistical distributions, including uniform, Poisson, normal, lognormal, Weibull and Gumbel (extreme value) distributions. Random numbers: Random variates from any distribution, 4 high-quality random number generators, low discrepancy sequences, shufflers. New in version 4.0 (November, 2010) Support for .NET Framework Version 4.0 and Visual Studio 2010 TPL Parallellized – multicore ready sparse linear program solver - can solve problems with more than 1 million variables. Mixed integer linear programming using a branch and bound algorithm. special functions: hypergeometric, Riemann zeta, elliptic integrals, Frensel functions, Dawson's integral. Full set of window functions for FFT's. Product  Price Update subscription Single Developer License $999  $399  Team License (3 developers) $1999  $799  Department License (8 developers) $3999  $1599  Site License (Unlimited developers in one physical location) $7999  $3199    NMath http://www.centerspace.net .NET math and statistics libraries matrix and vector classes random number generators Fast Fourier Transforms (FFTs) numerical integration linear programming linear regression curve and surface fitting optimization hypothesis tests analysis of variance (ANOVA) probability distributions principal component analysis cluster analysis built on the Intel Math Kernel Library (MKL), which contains highly-optimized, extensively-threaded versions of BLAS (Basic Linear Algebra Subroutines) and LAPACK (Linear Algebra PACKage). Product  Price Update subscription Single Developer License $1295 $388 Team License (5 developers) $5180 $1554   DotNumerics http://www.dotnumerics.com/NumericalLibraries/Default.aspx free DotNumerics is a website dedicated to numerical computing for .NET that includes a C# Numerical Library for .NET containing algorithms for Linear Algebra, Differential Equations and Optimization problems. The Linear Algebra library includes CSLapack, CSBlas and CSEispack, ports from Fortran to C# of LAPACK, BLAS and EISPACK, respectively. Linear Algebra (CSLapack, CSBlas and CSEispack). Systems of linear equations, eigenvalue problems, least-squares solutions of linear systems and singular value problems. Differential Equations. Initial-value problem for nonstiff and stiff ordinary differential equations ODEs (explicit Runge-Kutta, implicit Runge-Kutta, Gear's BDF and Adams-Moulton). Optimization. Unconstrained and bounded constrained optimization of multivariate functions (L-BFGS-B, Truncated Newton and Simplex methods).   Math.NET Numerics http://numerics.mathdotnet.com/ free an open source numerical library - includes special functions, linear algebra, probability models, random numbers, interpolation, integral transforms. A merger of dnAnalytics with Math.NET Iridium in addition to a purely managed implementation will also support native hardware optimization. constants & special functions complex type support real and complex, dense and sparse linear algebra (with LU, QR, eigenvalues, ... decompositions) non-uniform probability distributions, multivariate distributions, sample generation alternative uniform random number generators descriptive statistics, including order statistics various interpolation methods, including barycentric approaches and splines numerical function integration (quadrature) routines integral transforms, like fourier transform (FFT) with arbitrary lengths support, and hartley spectral-space aware sequence manipulation (signal processing) combinatorics, polynomials, quaternions, basic number theory. parallelized where appropriate, to leverage multi-core and multi-processor systems fully managed or (if available) using native libraries (Intel MKL, ACMS, CUDA, FFTW) provides a native facade for F# developers

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• FAQ: GridView Calculation with JavaScript - Displaying Quantity Total

  - by Vincent Maverick Durano

  Previously we've talked about how calculate the sub-totals and grand total in GridView here, how to format the numbers into a currency format and how to validate the quantity to just accept whole numbers using JavaScript here. One of the users in the forum (http://forums.asp.net) is asking if how to modify the script to display the quantity total in the footer. In this post I'm going to show you how to it. Basically we just need to modify the javascript CalculateTotals function and add the codes there for calculating the quantity total and display it in the footer. Here are the code blocks below:   <html xmlns="http://www.w3.org/1999/xhtml" > <head runat="server"> <title></title> <script type="text/javascript"> function CalculateTotals() { var gv = document.getElementById("<%= GridView1.ClientID %>"); var tb = gv.getElementsByTagName("input"); var lb = gv.getElementsByTagName("span"); var sub = 0; var total = 0; var indexQ = 1; var indexP = 0; var price = 0; var qty = 0; var totalQty = 0; for (var i = 0; i < tb.length; i++) { if (tb[i].type == "text") { ValidateNumber(tb[i]); price = lb[indexP].innerHTML.replace("$", "").replace(",", ""); sub = parseFloat(price) * parseFloat(tb[i].value); if (isNaN(sub)) { lb[i + indexQ].innerHTML = "0.00"; sub = 0; } else { lb[i + indexQ].innerHTML = FormatToMoney(sub, "$", ",", "."); ; } indexQ++; indexP = indexP + 2; if (isNaN(tb[i].value) || tb[i].value == "") { qty = 0; } else { qty = tb[i].value; } totalQty += parseInt(qty); total += parseFloat(sub); } } lb[lb.length - 2].innerHTML = totalQty; lb[lb.length - 1].innerHTML = FormatToMoney(total, "$", ",", "."); } function ValidateNumber(o) { if (o.value.length > 0) { o.value = o.value.replace(/[^\d]+/g, ''); //Allow only whole numbers } } function isThousands(position) { if (Math.floor(position / 3) * 3 == position) return true; return false; }; function FormatToMoney(theNumber, theCurrency, theThousands, theDecimal) { var theDecimalDigits = Math.round((theNumber * 100) - (Math.floor(theNumber) * 100)); theDecimalDigits = "" + (theDecimalDigits + "0").substring(0, 2); theNumber = "" + Math.floor(theNumber); var theOutput = theCurrency; for (x = 0; x < theNumber.length; x++) { theOutput += theNumber.substring(x, x + 1); if (isThousands(theNumber.length - x - 1) && (theNumber.length - x - 1 != 0)) { theOutput += theThousands; }; }; theOutput += theDecimal + theDecimalDigits; return theOutput; } </script> </head> <body> <form id="form1" runat="server"> <asp:gridview ID="GridView1" runat="server" ShowFooter="true" AutoGenerateColumns="false"> <Columns> <asp:BoundField DataField="RowNumber" HeaderText="Row Number" /> <asp:BoundField DataField="Description" HeaderText="Item Description" /> <asp:TemplateField HeaderText="Item Price"> <ItemTemplate> <asp:Label ID="LBLPrice" runat="server" Text='<%# Eval("Price","{0:C}") %>'></asp:Label> </ItemTemplate> <FooterTemplate> <b>Total Qty:</b> </FooterTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Quantity"> <ItemTemplate> <asp:TextBox ID="TXTQty" runat="server" onkeyup="CalculateTotals();"></asp:TextBox> </ItemTemplate> <FooterTemplate> <asp:Label ID="LBLQtyTotal" runat="server" Font-Bold="true" ForeColor="Blue" Text="0" ></asp:Label>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <b>Total Amount:</b> </FooterTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Sub-Total"> <ItemTemplate> <asp:Label ID="LBLSubTotal" runat="server" ForeColor="Green" Text="0.00"></asp:Label> </ItemTemplate> <FooterTemplate> <asp:Label ID="LBLTotal" runat="server" ForeColor="Green" Font-Bold="true" Text="0.00"></asp:Label> </FooterTemplate> </asp:TemplateField> </Columns> </asp:gridview> </form> </body> </html>   Here's the output below when you run it on the page: I hope someone find this post useful! Technorati Tags: ASP.NET,C#,JavaScript,GridView

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• Beware Sneaky Reads with Unique Indexes

  - by Paul White NZ

  A few days ago, Sandra Mueller (twitter | blog) asked a question using twitter’s #sqlhelp hash tag: “Might SQL Server retrieve (out-of-row) LOB data from a table, even if the column isn’t referenced in the query?” Leaving aside trivial cases (like selecting a computed column that does reference the LOB data), one might be tempted to say that no, SQL Server does not read data you haven’t asked for.  In general, that’s quite correct; however there are cases where SQL Server might sneakily retrieve a LOB column… Example Table Here’s a T-SQL script to create that table and populate it with 1,000 rows: CREATE TABLE dbo.LOBtest ( pk INTEGER IDENTITY NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( some_value, lob_data ) SELECT TOP (1000) N.n, @Data FROM Numbers N WHERE N.n <= 1000; Test 1: A Simple Update Let’s run a query to subtract one from every value in the some_value column: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; As you might expect, modifying this integer column in 1,000 rows doesn’t take very long, or use many resources.  The STATITICS IO and TIME output shows a total of 9 logical reads, and 25ms elapsed time.  The query plan is also very simple: Looking at the Clustered Index Scan, we can see that SQL Server only retrieves the pk and some_value columns during the scan: The pk column is needed by the Clustered Index Update operator to uniquely identify the row that is being changed.  The some_value column is used by the Compute Scalar to calculate the new value.  (In case you are wondering what the Top operator is for, it is used to enforce SET ROWCOUNT). Test 2: Simple Update with an Index Now let’s create a nonclustered index keyed on the some_value column, with lob_data as an included column: CREATE NONCLUSTERED INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); This is not a useful index for our simple update query; imagine that someone else created it for a different purpose.  Let’s run our update query again: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; We find that it now requires 4,014 logical reads and the elapsed query time has increased to around 100ms.  The extra logical reads (4 per row) are an expected consequence of maintaining the nonclustered index. The query plan is very similar to before (click to enlarge): The Clustered Index Update operator picks up the extra work of maintaining the nonclustered index. The new Compute Scalar operators detect whether the value in the some_value column has actually been changed by the update.  SQL Server may be able to skip maintaining the nonclustered index if the value hasn’t changed (see my previous post on non-updating updates for details).  Our simple query does change the value of some_data in every row, so this optimization doesn’t add any value in this specific case. The output list of columns from the Clustered Index Scan hasn’t changed from the one shown previously: SQL Server still just reads the pk and some_data columns.  Cool. Overall then, adding the nonclustered index hasn’t had any startling effects, and the LOB column data still isn’t being read from the table.  Let’s see what happens if we make the nonclustered index unique. Test 3: Simple Update with a Unique Index Here’s the script to create a new unique index, and drop the old one: CREATE UNIQUE NONCLUSTERED INDEX [UQ dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest (some_value) INCLUDE ( lob_data ) WITH ( FILLFACTOR = 100, MAXDOP = 1, SORT_IN_TEMPDB = ON ); GO DROP INDEX [IX dbo.LOBtest some_value (lob_data)] ON dbo.LOBtest; Remember that SQL Server only enforces uniqueness on index keys (the some_data column).  The lob_data column is simply stored at the leaf-level of the non-clustered index.  With that in mind, we might expect this change to make very little difference.  Let’s see: UPDATE dbo.LOBtest WITH (TABLOCKX) SET some_value = some_value - 1; Whoa!  Now look at the elapsed time and logical reads: Scan count 1, logical reads 2016, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   CPU time = 172 ms, elapsed time = 16172 ms. Even with all the data and index pages in memory, the query took over 16 seconds to update just 1,000 rows, performing over 52,000 LOB logical reads (nearly 16,000 of those using read-ahead). Why on earth is SQL Server reading LOB data in a query that only updates a single integer column? The Query Plan The query plan for test 3 looks a bit more complex than before: In fact, the bottom level is exactly the same as we saw with the non-unique index.  The top level has heaps of new stuff though, which I’ll come to in a moment. You might be expecting to find that the Clustered Index Scan is now reading the lob_data column (for some reason).  After all, we need to explain where all the LOB logical reads are coming from.  Sadly, when we look at the properties of the Clustered Index Scan, we see exactly the same as before: SQL Server is still only reading the pk and some_value columns – so what’s doing the LOB reads? Updates that Sneakily Read Data We have to go as far as the Clustered Index Update operator before we see LOB data in the output list: [Expr1020] is a bit flag added by an earlier Compute Scalar.  It is set true if the some_value column has not been changed (part of the non-updating updates optimization I mentioned earlier). The Clustered Index Update operator adds two new columns: the lob_data column, and some_value_OLD.  The some_value_OLD column, as the name suggests, is the pre-update value of the some_value column.  At this point, the clustered index has already been updated with the new value, but we haven’t touched the nonclustered index yet. An interesting observation here is that the Clustered Index Update operator can read a column into the data flow as part of its update operation.  SQL Server could have read the LOB data as part of the initial Clustered Index Scan, but that would mean carrying the data through all the operations that occur prior to the Clustered Index Update.  The server knows it will have to go back to the clustered index row to update it, so it delays reading the LOB data until then.  Sneaky! Why the LOB Data Is Needed This is all very interesting (I hope), but why is SQL Server reading the LOB data?  For that matter, why does it need to pass the pre-update value of the some_value column out of the Clustered Index Update? The answer relates to the top row of the query plan for test 3.  I’ll reproduce it here for convenience: Notice that this is a wide (per-index) update plan.  SQL Server used a narrow (per-row) update plan in test 2, where the Clustered Index Update took care of maintaining the nonclustered index too.  I’ll talk more about this difference shortly. The Split/Sort/Collapse combination is an optimization, which aims to make per-index update plans more efficient.  It does this by breaking each update into a delete/insert pair, reordering the operations, removing any redundant operations, and finally applying the net effect of all the changes to the nonclustered index. Imagine we had a unique index which currently holds three rows with the values 1, 2, and 3.  If we run a query that adds 1 to each row value, we would end up with values 2, 3, and 4.  The net effect of all the changes is the same as if we simply deleted the value 1, and added a new value 4. By applying net changes, SQL Server can also avoid false unique-key violations.  If we tried to immediately update the value 1 to a 2, it would conflict with the existing value 2 (which would soon be updated to 3 of course) and the query would fail.  You might argue that SQL Server could avoid the uniqueness violation by starting with the highest value (3) and working down.  That’s fine, but it’s not possible to generalize this logic to work with every possible update query. SQL Server has to use a wide update plan if it sees any risk of false uniqueness violations.  It’s worth noting that the logic SQL Server uses to detect whether these violations are possible has definite limits.  As a result, you will often receive a wide update plan, even when you can see that no violations are possible. Another benefit of this optimization is that it includes a sort on the index key as part of its work.  Processing the index changes in index key order promotes sequential I/O against the nonclustered index. A side-effect of all this is that the net changes might include one or more inserts.  In order to insert a new row in the index, SQL Server obviously needs all the columns – the key column and the included LOB column.  This is the reason SQL Server reads the LOB data as part of the Clustered Index Update. In addition, the some_value_OLD column is required by the Split operator (it turns updates into delete/insert pairs).  In order to generate the correct index key delete operation, it needs the old key value. The irony is that in this case the Split/Sort/Collapse optimization is anything but.  Reading all that LOB data is extremely expensive, so it is sad that the current version of SQL Server has no way to avoid it. Finally, for completeness, I should mention that the Filter operator is there to filter out the non-updating updates. Beating the Set-Based Update with a Cursor One situation where SQL Server can see that false unique-key violations aren’t possible is where it can guarantee that only one row is being updated.  Armed with this knowledge, we can write a cursor (or the WHILE-loop equivalent) that updates one row at a time, and so avoids reading the LOB data: SET NOCOUNT ON; SET STATISTICS XML, IO, TIME OFF;   DECLARE @PK INTEGER, @StartTime DATETIME; SET @StartTime = GETUTCDATE();   DECLARE curUpdate CURSOR LOCAL FORWARD_ONLY KEYSET SCROLL_LOCKS FOR SELECT L.pk FROM LOBtest L ORDER BY L.pk ASC;   OPEN curUpdate;   WHILE (1 = 1) BEGIN FETCH NEXT FROM curUpdate INTO @PK;   IF @@FETCH_STATUS = -1 BREAK; IF @@FETCH_STATUS = -2 CONTINUE;   UPDATE dbo.LOBtest SET some_value = some_value - 1 WHERE CURRENT OF curUpdate; END;   CLOSE curUpdate; DEALLOCATE curUpdate;   SELECT DATEDIFF(MILLISECOND, @StartTime, GETUTCDATE()); That completes the update in 1280 milliseconds (remember test 3 took over 16 seconds!) I used the WHERE CURRENT OF syntax there and a KEYSET cursor, just for the fun of it.  One could just as well use a WHERE clause that specified the primary key value instead. Clustered Indexes A clustered index is the ultimate index with included columns: all non-key columns are included columns in a clustered index.  Let’s re-create the test table and data with an updatable primary key, and without any non-clustered indexes: IF OBJECT_ID(N'dbo.LOBtest', N'U') IS NOT NULL DROP TABLE dbo.LOBtest; GO CREATE TABLE dbo.LOBtest ( pk INTEGER NOT NULL, some_value INTEGER NULL, lob_data VARCHAR(MAX) NULL, another_column CHAR(5) NULL, CONSTRAINT [PK dbo.LOBtest pk] PRIMARY KEY CLUSTERED (pk ASC) ); GO DECLARE @Data VARCHAR(MAX); SET @Data = REPLICATE(CONVERT(VARCHAR(MAX), 'x'), 65540);   WITH Numbers (n) AS ( SELECT ROW_NUMBER() OVER (ORDER BY (SELECT 0)) FROM master.sys.columns C1, master.sys.columns C2 ) INSERT LOBtest WITH (TABLOCKX) ( pk, some_value, lob_data ) SELECT TOP (1000) N.n, N.n, @Data FROM Numbers N WHERE N.n <= 1000; Now here’s a query to modify the cluster keys: UPDATE dbo.LOBtest SET pk = pk + 1; The query plan is: As you can see, the Split/Sort/Collapse optimization is present, and we also gain an Eager Table Spool, for Halloween protection.  In addition, SQL Server now has no choice but to read the LOB data in the Clustered Index Scan: The performance is not great, as you might expect (even though there is no non-clustered index to maintain): Table 'LOBtest'. Scan count 1, logical reads 2011, physical reads 0, read-ahead reads 0, lob logical reads 36015, lob physical reads 0, lob read-ahead reads 15992.   Table 'Worktable'. Scan count 1, logical reads 2040, physical reads 0, read-ahead reads 0, lob logical reads 34000, lob physical reads 0, lob read-ahead reads 8000.   SQL Server Execution Times: CPU time = 483 ms, elapsed time = 17884 ms. Notice how the LOB data is read twice: once from the Clustered Index Scan, and again from the work table in tempdb used by the Eager Spool. If you try the same test with a non-unique clustered index (rather than a primary key), you’ll get a much more efficient plan that just passes the cluster key (including uniqueifier) around (no LOB data or other non-key columns): A unique non-clustered index (on a heap) works well too: Both those queries complete in a few tens of milliseconds, with no LOB reads, and just a few thousand logical reads.  (In fact the heap is rather more efficient). There are lots more fun combinations to try that I don’t have space for here. Final Thoughts The behaviour shown in this post is not limited to LOB data by any means.  If the conditions are met, any unique index that has included columns can produce similar behaviour – something to bear in mind when adding large INCLUDE columns to achieve covering queries, perhaps. Paul White Email: [email protected] Twitter: @PaulWhiteNZ

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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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• Creating PHP Forms with show/hide functionality [migrated]

  - by ronquiq

  I want to create two reports and submit the report data to database by using two functions defined in a class: Here I have two buttons: "Create ES" and "Create RP". Rightnow, my forms are working fine, I can insert data successfully, but the problem was when I click on submit after filling the form data, the content is hiding and displays the fist div content "cs_content" and again I need to onclick to submit again. Could anyone give a solution for this. Requirement : When I click on "Create CS", I should be able to fill the form and submit data successfully with a message within "cs_content" and any form input errors, the errors should display within "cs_content". When I click on "Create RP", I should be able to fill the form and submit data successfully with a message within "rp_content" and any form input errors, the errors should display within "rp_content". home.php <?php require 'classes/class.report.php'; $report = new Report($db); ?> <html> <head> <script src="js/jqueryv1.10.2.js"></script> <script> $ (document).ready(function () { //$("#cs_content").show(); $('#cs').click(function () { $('#cs_content').fadeIn('slow'); $('#rp_content').hide(); }); $('#rp').click(function () { $('#rp_content').fadeIn('slow'); $('#cs_content').hide(); }); }); </script> </head> <body> <div class="container2"> <div style="margin:0px 0px;padding:3px 217px;overflow:hidden;"> <div id="cs" style="float:left;margin:0px 0px;padding:7px;"><input type="button" value="CREATE CS"></div> <div id="rp" style="float:left;margin:0px 0px;padding:7px;"><input type="button" value="CREATE RP"></div><br> </div> <div id="cs_content"> <?php $report->create_cs_report(); ?> </div> <div id="rp_content" style="display:none;"> <?php $report->create_rp_report(); ?> </div> </div> </body> </html> class.report.php <?php class Report { private $db; public function __construct($database){ $this->db = $database; } public function create_cs_report() { if (isset($_POST['create_es_report'])) { $report_name = htmlentities($_POST['report_name']); $from_address = htmlentities($_POST['from_address']); $subject = htmlentities($_POST['subject']); $reply_to = htmlentities($_POST['reply_to']); if (empty($_POST['report_name']) || empty($_POST['from_address']) || empty($_POST['subject']) || empty($_POST['reply_to'])) { $errors[] = '<span class="error">All fields are required.</span>'; } else { if (isset($_POST['report_name']) && empty($_POST['report_name'])) { $errors[] = '<span class="error">Report Name is required</span>'; } else if (!ctype_alnum($_POST['report_name'])) { $errors[] = '<span class="error">Report Name: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['from_address']) && empty($_POST['from_address'])) { $errors[] = '<span class="error">From address is required</span>'; } else if (filter_var($_POST['from_address'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid From address</span>'; } if (isset($_POST['subject']) && empty($_POST['subject'])) { $errors[] = '<span class="error">Subject is required</span>'; } else if (!ctype_alnum($_POST['subject'])) { $errors[] = '<span class="error">Subject: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['reply_to']) && empty($_POST['reply_to'])) { $errors[] = '<span class="error">Reply To is required</span>'; } else if (filter_var($_POST['reply_to'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid Reply-To address</span>'; } } if (empty($errors) === true) { $query = $this->db->prepare("INSERT INTO report(report_name, from_address, subject, reply_to) VALUES (?, ?, ?, ?) "); $query->bindValue(1, $report_name); $query->bindValue(2, $from_address); $query->bindValue(3, $subject); $query->bindValue(4, $reply_to); try { $query->execute(); } catch(PDOException $e) { die($e->getMessage()); } header('Location:home.php?success'); exit(); } } if (isset($_GET['success']) && empty($_GET['success'])) { header('Location:home.php'); echo '<span class="error">Report is succesfully created</span>'; } ?> <form action="" method="POST" accept-charset="UTF-8"> <div style="font-weight:bold;padding:17px 80px;text-decoration:underline;">Section A</div> <table class="create_report"> <tr><td><label>Report Name</label><span style="color:#A60000">*</span></td> <td><input type="text" name="report_name" required placeholder="Name of the report" value="<?php if(isset($_POST["report_name"])) echo $report_name; ?>" size="30" maxlength="30"> </td></tr> <tr><td><label>From</label><span style="color:#A60000">*</span></td> <td><input type="text" name="from_address" required placeholder="From address" value="<?php if(isset($_POST["from_address"])) echo $from_address; ?>" size="30"> </td></tr> <tr><td><label>Subject</label><span style="color:#A60000">*</span></td> <td><input type="text" name="subject" required placeholder="Subject" value="<?php if(isset($_POST["subject"])) echo $subject; ?>" size="30"> </td></tr> <tr><td><label>Reply To</label><span style="color:#A60000">*</span></td> <td><input type="text" name="reply_to" required placeholder="Reply address" value="<?php if(isset($_POST["reply_to"])) echo $reply_to; ?>" size="30"> </td></tr> <tr><td><input type="submit" value="create report" style="background:#8AC007;color:#080808;padding:6px;" name="create_es_report"></td></tr> </table> </form> <?php //IF THERE ARE ERRORS, THEY WOULD BE DISPLAY HERE if (empty($errors) === false) { echo '<div>' . implode('</p><p>', $errors) . '</div>'; } } public function create_rp_report() { if (isset($_POST['create_rp_report'])) { $report_name = htmlentities($_POST['report_name']); $to_address = htmlentities($_POST['to_address']); $subject = htmlentities($_POST['subject']); $reply_to = htmlentities($_POST['reply_to']); if (empty($_POST['report_name']) || empty($_POST['to_address']) || empty($_POST['subject']) || empty($_POST['reply_to'])) { $errors[] = '<span class="error">All fields are required.</span>'; } else { if (isset($_POST['report_name']) && empty($_POST['report_name'])) { $errors[] = '<span class="error">Report Name is required</span>'; } else if (!ctype_alnum($_POST['report_name'])) { $errors[] = '<span class="error">Report Name: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['to_address']) && empty($_POST['to_address'])) { $errors[] = '<span class="error">to address is required</span>'; } else if (filter_var($_POST['to_address'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid to address</span>'; } if (isset($_POST['subject']) && empty($_POST['subject'])) { $errors[] = '<span class="error">Subject is required</span>'; } else if (!ctype_alnum($_POST['subject'])) { $errors[] = '<span class="error">Subject: Whitespace is not allowed, only alphabets and numbers are required</span>'; } if (isset($_POST['reply_to']) && empty($_POST['reply_to'])) { $errors[] = '<span class="error">Reply To is required</span>'; } else if (filter_var($_POST['reply_to'], FILTER_VALIDATE_EMAIL) === false) { $errors[] = '<span class="error">Please enter a valid Reply-To address</span>'; } } if (empty($errors) === true) { $query = $this->db->prepare("INSERT INTO report(report_name, to_address, subject, reply_to) VALUES (?, ?, ?, ?) "); $query->bindValue(1, $report_name); $query->bindValue(2, $to_address); $query->bindValue(3, $subject); $query->bindValue(4, $reply_to); try { $query->execute(); } catch(PDOException $e) { die($e->getMessage()); } header('Location:home.php?success'); exit(); } } if (isset($_GET['success']) && empty($_GET['success'])) { header('Location:home.php'); echo '<span class="error">Report is succesfully created</span>'; } ?> <form action="" method="POST" accept-charset="UTF-8"> <div style="font-weight:bold;padding:17px 80px;text-decoration:underline;">Section A</div> <table class="create_report"> <tr><td><label>Report Name</label><span style="color:#A60000">*</span></td> <td><input type="text" name="report_name" required placeholder="Name of the report" value="<?php if(isset($_POST["report_name"])) echo $report_name; ?>" size="30" maxlength="30"> </td></tr> <tr><td><label>to</label><span style="color:#A60000">*</span></td> <td><input type="text" name="to_address" required placeholder="to address" value="<?php if(isset($_POST["to_address"])) echo $to_address; ?>" size="30"> </td></tr> <tr><td><label>Subject</label><span style="color:#A60000">*</span></td> <td><input type="text" name="subject" required placeholder="Subject" value="<?php if(isset($_POST["subject"])) echo $subject; ?>" size="30"> </td></tr> <tr><td><label>Reply To</label><span style="color:#A60000">*</span></td> <td><input type="text" name="reply_to" required placeholder="Reply address" value="<?php if(isset($_POST["reply_to"])) echo $reply_to; ?>" size="30"> </td></tr> <tr><td><input type="submit" value="create report" style="background:#8AC007;color:#080808;padding:6px;" name="create_rp_report"></td></tr> </table> </form> <?php //IF THERE ARE ERRORS, THEY WOULD BE DISPLAY HERE if (empty($errors) === false) { echo '<div>' . implode('</p><p>', $errors) . '</div>'; } } }//Report CLASS ENDS

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• WPF, PreviewKeyDown event and underscore char

  - by commanderz

  Hi, I'm catching key hits with PreviewKeyDown event in my WPF component. I need to distinguish characters being typed: letters vs. numbers vs. underscore vs. anything else. Letters and numbers work fine (just convert the Key property of the KeyEventArgs object to string and work with character 0 of that string), but this won't work for underscore. It's ToString value depends on localized keyboard settings (it shows up as "OemMinus" on EN/US keyboard and "OemQuestion" on CZ/QWERTY keyboard). So how can I RELIABLY find out, if the typed char is underscore in the PreviewKeyDown event? Thanks for any help

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• Genetic algorithms

  - by daniels

  I'm trying to implement a genetic algorithm that will calculate the minimum of the Rastrigin functon and I'm having some issues. I need to represent the chromosome as a binary string and as the Rastrigin's function takes a list of numbers as a parameter, how can decode the chromosome to a list of numbers? Also the Rastrigin's wants the elements in the list to be -5.12<=x(i)<=5.12 what happens if when i generate the chromosome it will produce number not in that interval? I'm new to this so help and explanation that will aid me in understanding will be highly appreciated. Thanks.

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• MS Chart control with WPF C#

  - by Birgir Hrafn Sigurðsson

  Hello, Ive got a MS Chart control and it works just fine except that I can't figure out how to "format" the Y-Axis. I am adding a lot of double numbers into a Serie but when the double numb are actually whole numbers (20.000000.....) the Y-Axis on my chart shows 20. example: this serie : 12.32 11.00 10.13 would actually show up like this: 12.32 11 10.13 I have tried formatting the data as I insert it into the serie like this: serie.Points.AddXY(date.ToString(),double[i].ToString("##.##")); but that doesn't seem to work. I've tried to search for a place to format it in Chart.Series[0].* and Chart.ChartAreas[0].* but I didn't find it there. Thanks in advance, Regards, Birgir Hrafn

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• PHP preg_replace oddity with £ pound sign and ã

  - by Barry Ramsay

  Hello I am applying the following function <?php function replaceChar($string){ $new_string = preg_replace("/[^a-zA-Z0-9\sçéèêëñòóôõöàáâäåìíîïùúûüýÿ]/", "", $string); return $new_string; } $string = "This is some text and numbers 12345 and symbols !£%^#&$ and foreign letters éèêëñòóôõöàáâäåìíîïùúûüýÿ"; echo replaceChar($string); ?> which works fine but if I add ã to the preg_replace like $new_string = preg_replace("/[^a-zA-Z0-9\sçéèêëñòóôõöàáâãäåìíîïùúûüýÿ]/", "", $string); $string = "This is some text and numbers 12345 and symbols !£%^#&$ and foreign letters éèêëñòóôõöàáâäåìíîïùúûüýÿã"; It conflicts with the pound sign £ and replaces the pound sign with the unidentified question mark in black square. This is not critical but does anyone know why this is? Thank you, Barry

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• Formula for calculating Exotic wagers such as Trifecta and Superfecta

  - by JohnnyCantCode

  I am trying to create an application that will calculate the cost of exotic parimutuel wager costs. I have found several for certain types of bets but never one that solves all the scenarios for a single bet type. If I could find an algorithm that could calculate all the possible combinations I could use that formula to solve my other problems. Additional information: I need to calculate the permutations of groups of numbers. For instance; Group 1 = 1,2,3 Group 2 = 2,3,4 Group 3 = 3,4,5 What are all the possible permutation for these 3 groups of numbers taking 1 number from each group per permutation. No repeats per permutation, meaning a number can not appear in more that 1 position. So 2,4,3 is valid but 2,4,4 is not valid. Thanks for all the help.

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• Multiple JOIN and SELECT Statements from eight tables

  - by user1486004

  I am trying to make an SQL statement that takes eight different numbers and searches eight different tables from one database for the corresponding value. I keep getting invalid syntax, but I can't figure out why. Here is my code: SELECT cable_length.ID, drawing.ID, optional.ID, output_type.ID, pressure_range.ID, pressure_type.ID, series.ID, termination.ID FROM ( SELECT value AS cable_length FROM A1 WHERE A1.id = %s JOIN SELECT value AS drawing FROM A2 WHERE A2.id = %s, JOIN SELECT value AS optional FROM A3 WHERE A3.id = %s, JOIN SELECT value AS output_type FROM A4 WHERE A4.id = %s, JOIN SELECT value AS pressure_range FROM A5 WHERE A5.id = %s, JOIN SELECT value AS pressure_type FROM A6 WHERE A6.id = %s, JOIN SELECT value AS series FROM A7 WHERE A7.id = %s, JOIN SELECT value AS termination FROM A8 WHERE A8.id = %s ); The %s will be changed to numbers only. The column name in each database is "ID" and "Value". I want to search by "ID" and return "Value". Any help is greatly appreciated.

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• Java char array to int

  - by Kyle

  Hello, Is it possible to convert a char[] array containing numbers into an int? Thanks ~ Kyle.

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• Big 0 theta notation

  - by niggersak

  Can some pls help with the solution Use big-O notation to classify the traditional grade school algorithms for addition and multiplication. That is, if asked to add two numbers each having N digits, how many individual additions must be performed? If asked to multiply two N-digit numbers, how many individual multiplications are required? Suppose f is a function that returns the result of reversing the string of symbols given as its input, and g is a function that returns the concatenation of the two strings given as its input. If x is the string hrwa, what is returned by g(f(x),x)? Explain your answer - don't just provide the result!

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• django select max field from mysql when column is varchar

  - by doza

  Hi, Using Django 1.1, I am trying to select the maximum value from a varchar column (in MySQL.) The data stored in the column looks like: 9001 9002 9017 9624 10104 11823 (In reality, the numbers are much bigger than this.) This worked until the numbers incremented above 10000: Feedback.objects.filter(est__pk=est_id).aggregate(sid=Max('sid')) Now, that same line would return 9624 instead of 11823. I'm able to run a query directly in the DB that gives me what I need, but I can't figure out the best way to do this in Django. The query would be: select max(sid+0) from Feedback; Any help would be much appreciated. Thanks!

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• Database design - alternatives for Entity Attribute Value (EAV)

  - by Bob

  Hi, see http://stackoverflow.com/questions/695752/product-table-many-kinds-of-product-each-product-has-many-parameters for similar topic. My question: i want to design a database, that will be used for a production facility of different types of products where each product has its own (number of) parameters. because i want the serial numbers to be in one tabel for overview purposes i have a problem with these different paraeters . One solution could be EAV, but it has its downsides, certainly because we have +- 5 products with every product +- 20.000 serial numbers (records). it looks a bit overkill to me... I just don't know how one could design a database so that you have an attribute in a mastertable that says: 'hey, you could find details of this record in THAT detail-table". 'in a way that you qould easely query the results) currenty i am using Visual Basic & Acces 2007. but i'm going to Visual Basic & MySQL. thanks for your help. Bob

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• Looking for calculator source code, BSD-licensed

  - by Horace Ho

  I have an urgent project which need many functions of a calculator (plus a few in-house business rule formulas). As I won't have time to re-invent the wheel so I am looking for source code directly. Requirements: BSD licensed (GPL won't help) in c/c++ programming language 32-bit CPU minimum dependency on platform API/data structure best with both RPN and prefix notation supported emulator/simulator code also acceptable (if not impossible to add custom formula) with following functions (from wikipedia) Scientific notation for calculating large numbers floating point arithmetic logarithmic functions, using both base 10 and base e trigonometry functions (some including hyperbolic trigonometry) exponents and roots beyond the square root quick access to constants such as pi and e plus hexadecimal, binary, and octal calculations, including basic Boolean math fractions optional statistics and probability calculations complex numbers programmability equation solving

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• OpenCV's cvKMeans2 - chosing clusters

  - by Goffrey

  Hi, I'm using cvKMeans2 for clustering, but I'm not sure, how it works in general - the part of choosing clusters. I thought that it set the first positions of clusters from given samples. So it means that in the end of clustering process would every cluster has at least one sample - in the output array of cluster labels will be full range of numbers (for 100 clusters - numbers 0 to 99). But as I checked output labels, I realised that some labels weren't used at all and only some were used. So, does anyone know, how it works? Or how should I use the parameters of cvKMeans2 to do what I want (cause I'm not sure if I use them right)? I'm using cvKMeans2 function also with optional parameters: cvKMeans2(descriptorMat, N_CLUSTERS, clusterLabels, cvTermCriteria( CV_TERMCRIT_EPS+CV_TERMCRIT_ITER, 10, 1.0), 1, 0, 0, clusterCenters, 0) Thanks for any advices!

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• Regular expressions in findstr

  - by Johannes Rössel

  I'm doing a little string validation with findstr and its /r flag to allow for regular expressions. In particular I'd like to validate integers. The regex ^[0-9][0-9]*$ worked fine for non-negative numbers but since I now support negative numbers as well I tried ^([1-9][0-9]*|0|-[1-9][0-9]*)$ for either positive or negative integers or zero. The regex works fine theoretically. I tested it in PowerShell and it matches what I want. However, with findstr /r /c:"^([1-9][0-9]*|0|-[1-9][0-9]*)$" it doesn't. While I know that findstr doesn't have the most advanced regex support (even below Notepad++ which is probably quite an achievement), I would have expected such simple expressions to work. Any ideas what I'm doing wrong here?

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• reset, Tweener, AS3

  - by VideoDnd

  How do I reset my numbers after they count? I want something like an onComplete function. DESCRIPTION My animation advances 120 pixels from it's current position, then flys off the stage. It was looping, and would yoyo to the bottom before advancing. I don't want my numbers yoyoing or flying off the stage. My numbers must move 120 pixels forward each count, then return. NumbersView.as 'the code works, but in a messed up way as described' package { import flash.display.DisplayObject; import flash.display.MovieClip; import flash.utils.Dictionary; import flash.events.Event; import caurina.transitions.Tweener; public class NumbersView extends MovieClip { private var _listItems:Array; private var previousNums:Array; private const numHeight:int = 120; public function NumbersView() { _listItems = new Array(); previousNums = new Array(); //Tweener.init(); var item:NumberImage; for (var i:Number = 0; i < 9; i++) { item = new NumberImage(); addChild(item); item.x = i * item.width; _listItems.push(item); } } public function setTime($number:String):void { var nums:Array = $number.split(""); //trace("$number = " + $number); for (var i:Number = 0; i < nums.length; i++) { if (nums[i] == previousNums[i]) continue; Tweener.removeTweens(_listItems[i]); //newY:int = -numHeight; var newY:int = int(nums[i]) * -numHeight; trace("newY = " + newY); trace("currY = " + _listItems[i].y); /*----------------------PROBLEM AREA, RIGHT HERE------------------------*/ //if (_listItems[i].y < 0) _listItems[i].y = numHeight;// //Tweener.addTween(_listItems[i], { y:newY, time:3 } );// Tweener.addTween(_listItems[i], { y:_listItems[i].y+newY, time:3 } );// } previousNums = nums; } } } Tweener Example http://hosted.zeh.com.br/tweener/docs/en-us/parameters/onComplete.html

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• create a random sequence, skip to any part of the sequence

  - by Michael Xu

  Hi everyone, In Linux. There is an srand() function, where you supply a seed and it will guarantee the same sequence of pseudorandom numbers in subsequent calls to the random() function afterwards. Lets say, I want to store this pseudo random sequence by remembering this seed value. Furthermore, let's say I want the 100 thousandth number in this pseudo random sequence later. One way, would be to supply the seed number using srand(), and then calling random() 100 thousand times, and remembering this number. Is there a better way of skipping all 99,999 other numbers in the pseudo random list and directly getting the 100 thousandth number in the list. thanks, m

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• Flex/Air : Text Area with Line Number Filtering

  - by Ajay

  I need to have a Text Area With Line Numbers, & once the Text File is Imported to the Text Area.. the user must be able to select the line numbers & see the filtered output. I have implemented the same with Numeric steppers. I am in search of an enhanced component. are there better Advanced Components for Textarea ? Any Advanced Textarea component with built-in Search/Replace/Filter Capabilities ? Cheers, Ajay

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• Asp.net text box is only returning the first value

  - by queryne

  C sharp newbie question...I have a simple asp.net form that has a textbox that collects phonenumbers to send SMS messages. If I bypass the form and hardcode the numbers using the following format: "2133211234",#1233211234" the code works fine. However when i try to use this same format using my form, the sms will ONLY send to the first number. I have a feeling i'm missing out on some property on my form that will accept all of the values. also any idea how how i can add some lines of code that will allow users to enter numbers like this: 3123211234,4123212344 and have it converted to the format above when the number is submitted? Any ideas? Thanks in advance.

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• ansi-c fscanf problem

  - by mongoose

  hi i read the file as follows fscanf(fp,"%f %f %f",&*(p1+i), &*(p2+i), &*(p3+i)); my file's lines consists of three floating point numbers... the problem i have is that in the file let's say i have some floating points with let's say maximum of two digits after the dot. but when i ask c to print those values using different formatting, for example %lf,%.2lf,%.4lf... it starts to play with the digits... my only concern is this, if i have let's say 1343.23 in the file, then will c use this value exactly as it is in computations or it will play with the digits after the dot. if it will play, then how is it possible to make it so that it uses floating point numbers exactly as they are? for example in last case even if i ask it to print that value using %.10lf i would expect it to print only 1343.2300000000.? thanks a lot!

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• MySQL differences between to select queries

  - by bpmccain

  I have two mysql queries that return a column of phone numbers. I want am trying to end up with a list of phone numbers that are in one list, but not in the other. So the two queries I have are: SELECT phone FROM civicrm_phone phone LEFT JOIN civicrm_participant participant ON phone.contact_id = participant.contact_id WHERE phone.is_primary = 1 AND participant.id IS NULL and SELECT phone FROM civicrm_phone phone LEFT JOIN civicrm_participant participant ON phone.contact_id = participant.contact_id WHERE phone.is_primary = 1 AND participant.id IS NOT NULL And before anyone asks, the above two queries do not provide mutually exclusive results (based on using IS NULL and IS NOT NULL for the last WHERE statement), since we have related individuals in the database who use the same phone number, but do not necessarily all have a participant.id. Thanks for any help.

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• Why are my "tel:" links not working

  - by Griffo

  I have a tableView which has cells with phone numbers. The app is not dialing the numbers though. See the code below - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { if (indexPath.section == 2) { UITableViewCell *selectedCell = [tableView cellForRowAtIndexPath:indexPath]; NSString *numberToDial = [NSString stringWithFormat:@"tel:%@", selectedCell.detailTextLabel.text]; NSLog(@"%@",numberToDial); [[UIApplication sharedApplication] openURL:[NSURL URLWithString:numberToDial]]; } } Console ouput: 2010-03-08 01:32:30.830 AIB[1217:207] tel:01 8350098 As you can see, the number goes to the console, but doesn't get dialled. The weird thing is, if I change the last statement to this: [[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"tel:171"]]; the phone dials the number 171 without any issue

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