I want to use an external library (here the (high precision arithmetic) library MPIR, but I guess the problem applies to other libraries as well) in my C code which is called via MEX from Matlab. To this end, I built MPIR using MinGW via the commands make, make install and make check, which performed without error (nevertheless I am not completely sure whether all libraries are in the correct places (see locations of file described below) - how can I test that?). Now I set up a small test program myfile.cpp with header myfile.h, which looks like the following:
// this is myfile.cpp
#include "mex.h"
#include "mpir.h"
#include "myfile.h"
#include <stdio.h>
void myfile(double a)
{
mpf_t b;
mp_bitcnt_t bct = 350;
double f = 10.0, g = 3.0;
mpf_set_default_prec(bct);
mpf_init(b);
mpf_set_d (b, f);
gmp_printf("b is %.*Ff \n",120,b );
mpf_clear(b);
}
where the various calls refer to high precision types of the MPIR library, with header file
// this is myfile.h
#include "mex.h"
#include "mpir.h"
#include <stdio.h>
void myfile(double a);
I hoped to call this routine by the mex file mexlib.cpp, which reads:
// this is mexlib.cpp
#include "mex.h"
#include "mpir.h"
#include "myfile.h"
#include <stdio.h>
void mexFunction(
int nlhs,
mxArray *plhs[],
int nrhs,
const mxArray *prhs[]
)
{
double a;
a = mxGetScalar(prhs[0]); /* create pointer to the real data in the input arguments */
myfile(a); /* call the computational routine */
return;
}
The MPIR base directory is C:/MPIR/mpir-2.7.0/, in which I can see the files mpir.h, gmp.h, libmpir.la, among many others, and folders /.libs/, /mpf/, /mpz/, etc. In the /.libs/ folder, there are the files libmpir.la, libmpir.dll.a, libmpir-16.dll, libmpir-3.dll.def, among many others, but eg. no file "libmpir.a" or libmpirdll.a", which I was looking for when learning from some other questions here.
In Matlab, I tried to compile it via mex using the commands
mex -IC:/MPIR/mpir-2.7.0/ -LC:/MPIR/mpir-2.7.0/.libs mexlib.cpp myfile.cpp -v , or
mex -IC:/MPIR/mpir-2.7.0/ -LC:/MPIR/mpir-2.7.0/ mexlib.cpp myfile.cpp -v .
It responded with errors stating:
"myfile.obj : error LNK2019: unresolved external symbol __imp___gmpf_clear referenced in function "void __cdecl myfile(double)" (?myfile@@YAXN@Z)"
and similar lines for the other functions called in myfile.cpp , and exited with
"mexlib.mexw64 : fatal error LNK1120: 5 unresolved externals."
In the mex documentation, I read that the flags -L and -l point to locations with files ending with .lib (on Windows).
How can I point it to the ".h" files - or is it not what I need? I tried to add some paths to the PATH environment variable, also the MinGW paths, which did not help.
It is a Windows 7 PC with the only compiler found by Matlab being the Microsoft SDK 7.1. Using the -v flag shows as "COMPILER = cl"... is this the SDK? There is also gcc somewhere ( I guesss in the MinGW folder?).
I guess I am confused of all the #includes, header file constructs in C and compiler options; then, of most help to me would be an illumination of which ones are needed (best with an example).
Thanks in advance!
