mexme - write MEX files in no time 1.0

mexme automates the process of writing MEX files. You give mexme a snippet of C which just does numeric computations, as well a list of arguments, and it generates a valid MEX .c file. New in version 1.1, it writes tedious input and output validation code for you. This way you can write a MEX file without manually coding calls to mx* API functions. It's inspired by SciPy's weave function.Example: translate this piece of (non-vectorizable) .m code that applies a recursive filter into C:function [y] = myrecursivefilter(x,alpha) y = zeros(size(x)); y(1) = x(1)*alpha; for ii = 2:length(x) y(ii) = y(ii-1)*(1-alpha) + x(ii)*alpha; endendStep 1: Write myrecursivefilter.csnip which does the same thing as the m file:y[0] = x[0]*alpha;for(mwSize i = 1; i < x_length; i++) { y[i] = x[i]*alpha + y[i-1]*(1-alpha);}Step 2: Define arguments to your function (in Matlab):inputargs = [InputNum('x'),... InputNum('alpha',true,true,'double','alpha > 0 && alpha < 1)]; %scalar %The last conditionoutputarg = OutputNum('y','x_length,1');Step 3: Generate a fully fledged .c file that can be compiled with mex:cfile = mexme('myrecursivefilter.csnip',inputargs,outputarg)writefile('myfilt.c',cfile);mex myfilt.cx = randn(1e6,1);y = myfilt(x,.1);plot([x,y])cfile =/*#include and #define not shown*/#include "mexmetypecheck.c"void mexFunction( int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[] ){/*Input output boilerplate*/ if(nlhs != 1 || nrhs != 2) mexErrMsgTxt("Function must be called with 2 arguments and has 1 return values"); const mxArray *x_ptr = prhs[0]; const mwSize x_m = mxGetM(x_ptr); const mwSize x_n = mxGetN(x_ptr); const mwSize x_length = x_m == 1 ? x_n : x_m; const mwSize x_numel = mxGetNumberOfElements(x_ptr); const int x_ndims = mxGetNumberOfDimensions(x_ptr); const mwSize *x_size = mxGetDimensions(x_ptr); const double *x = (double *) mxGetData(x_ptr); const mxArray *alpha_ptr = prhs[1]; if(mxGetNumberOfElements(alpha_ptr) != 1) mexErrMsgTxt("Argument alpha (#2) must be scalar"); const double alpha = (double) mxGetScalar(alpha_ptr); if(!(alpha > 0 && alpha < 1)) mexErrMsgTxt("Argument alpha (#2) did not pass test "alpha > 0 && alpha < 1""); mwSize y_dims[] = {x_length,1}; plhs[0] = mxCreateNumericArray(2,y_dims,mxDOUBLE_CLASS,mxREAL); mxArray **y_ptr = &plhs[0]; double *y = (double *) mxGetData(*y_ptr); /*Actual function*/#include "myfilt.csnip"}For every argument that you define, mexme generates extra "magic" variables. For example, if the variable is x, then in C:x is the datax_m is the size of the first dimensionx_n is the size of the second dimensionx_length is the length of a vectorx_numel is the number of elements in an arrayx_ndims is the numer of dimensionsx_size is equivalent to the Matlab code size(x)x_ptr is a reference to the mxArray that contains the x dataAnd if x is complex, x_r and x_i are the real and imaginary components of the data.mexme currently does not support sparse data or non-numeric types but it does support full numeric arrays of any type (int8, single, double, etc.).

Requirements:	No special requirements
Platforms:	Matlab
Keyword:	Alpha Ptr,  Dims,  Double,  Mexerrmsgtxtquotargument,  Mxgetdatax Ptr,  Mxgetdimensionsx Ptr,  Mxgetnumberofdimensionsx Ptr,  Prhs,  Scalarquot,  Size
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