MATLAB: How to transfer the size of the array to mexFunction

allocatefortranmex

      #include "fintrf.h"
      SUBROUTINE mexFunction(nlhs, plhs, nrhs, prhs)
      IMPLICIT NONE
      mwPointer plhs(*), prhs(*)
      integer nlhs, nrhs
      mwPointer mxGetPr
      mwPointer mxGetM
      mwPointer mxCreateDoubleMatrix
      mwPointer P1,P2,P3
      REAL*8 R1,R2,R3
      %R1 is integer number
      %R2(R1,1) - size of R2
      %R3(R1-2,11) - size of R3
      P1 = mxGetPr(prhs(1))
      P2 = mxGetPr(prhs(2))
      CALL mxCopyPtrToREAL8(P1,R1,1)
      CALL mxCopyPtrToREAL8(P2,R2,1)
      plhs(1) = mxCreateDoubleMatrix(M-2,11,0)
      P3 = mxGetPr(plhs(1))
      CALL ProgramName(R1,R2,R3)
      CALL mxCopyREAL8ToPtr(R3,P3,(M-2)*11)    
      return
      end
This program has 2 input parameters: R1 and R2. Dimensions R2 = R2 (R1). Output parameter R3 has dimensions R3 (R1-2, 11). How can I implement this?

Best Answer

Try this (caveat, untested). Don't pass in the row size of the matrix ... just pass in the matrix only. Let the code figure out the row size via mxGetM. I highly advise you add some argument checking into this as well. E.g., make sure you have exactly one full double 2D real input, and that nlhs <= 1.
      #include "fintrf.h"
      SUBROUTINE mexFunction(nlhs, plhs, nrhs, prhs)
      IMPLICIT NONE
      mwPointer plhs(*), prhs(*)
      integer nlhs, nrhs
      mwPointer mxGetPr
      mwPointer mxGetM
      mwPointer mxCreateDoubleMatrix
      mwPointer P1, P3
      integer M
      mwSize Cm, Cn
      integer*4 ComplexFlag
      P1 = mxGetPr(prhs(1))
      M = mxGetM(prhs(1))
      if( M <= 2 ) then
          call mexErrMsgTxt("Input size is too small")
      endif
      Cm = M - 2
      Cn = 11
      ComplexFlag = 0
      plhs(1) = mxCreateDoubleMatrix(Cm,Cn,ComplexFlag)
      P3 = mxGetPr(plhs(1))
      CALL ProgramName( %val(P1), M, %val(P3) )
      return
      end
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