Reading/Writing MAT files in C

[Jerome]

HI,
I am trying to compile the following code, but am unsuccessful. I have not seen any documentation of using the mat.h file. Any suggestions would be great

#include <stdio.h>
#include <stdlib.h>
#include "mat.h"

int diagnose(const char *file) {
MATFile *pmat;
const char **dir;
const char *name;
int ndir;
int i;
mxArray *pa;

printf("Reading file %s...\n\n", file);

/*
* * Open file to get directory
* */
pmat = matOpen(file, "r");
if (pmat == NULL) {
printf("Error opening file %s\n", file);
return(1);
}

/*
* * get directory of MAT-file
* */
dir = (const char **)matGetDir(pmat, &ndir);
if (dir == NULL) {
printf("Error reading directory of file %s\n", file);
return(1);
} else {
printf("Directory of %s:\n", file);
for (i=0; i < ndir; i++)
printf("%s\n",dir[i]);
}
mxFree(dir);

/* In order to use matGetNextXXX correctly, reopen file to read in headers. */
if (matClose(pmat) != 0) {
printf("Error closing file %s\n",file);
return(1);
}
pmat = matOpen(file, "r");
if (pmat == NULL) {
printf("Error reopening file %s\n", file);
return(1);
}

/* Get headers of all variables */
printf("\nExamining the header for each variable:\n");
for (i=0; i < ndir; i++) {
pa = matGetNextVariableInfo(pmat, &name);
if (pa == NULL) {
printf("Error reading in file %s\n", file);
return(1);
}
/* Diagnose header pa */
printf("According to its header, array %s has %d dimensions\n",
name, mxGetNumberOfDimensions(pa));
if (mxIsFromGlobalWS(pa))
printf(" and was a global variable when saved\n");
else
printf(" and was a local variable when saved\n");
mxDestroyArray(pa);
}

/* Reopen file to read in actual arrays. */
if (matClose(pmat) != 0) {
printf("Error closing file %s\n",file);
return(1);
}
pmat = matOpen(file, "r");
if (pmat == NULL) {
printf("Error reopening file %s\n", file);
return(1);
}

/* Read in each array. */
printf("\nReading in the actual array contents:\n");
for (i=0; i<ndir; i++) {
pa = matGetNextVariable(pmat, &name);
if (pa == NULL) {
printf("Error reading in file %s\n", file);
return(1);
}
/*
* * Diagnose array pa
* */
printf("According to its contents, array %s has %d dimensions\n",
name, mxGetNumberOfDimensions(pa));
if (mxIsFromGlobalWS(pa))
printf(" and was a global variable when saved\n");
else
printf(" and was a local variable when saved\n");
mxDestroyArray(pa);
}

if (matClose(pmat) != 0) {
printf("Error closing file %s\n",file);
return(1);
}
printf("Done\n");
return(0);
}

int main(int argc, char **argv)
{

int result;

if (argc > 1)
result = diagnose(argv[1]);
else{
result = 0;
printf("Usage: matdgns <matfile>");
printf(" where <matfile> is the name of the MAT-file");
printf(" to be diagnosed\n");
}

return (result==0)?EXIT_SUCCESS:EXIT_FAILURE;

}

[Ben]

"Jerome " <the_...@hotmail.com> wrote in message <jojci3$he4$1...@newscl01ah.mathworks.com>...

> HI,
> I am trying to compile the following code, but am unsuccessful. I have not seen any documentation of using the mat.h file. Any suggestions would be great
>
> #include <stdio.h>
> #include <stdlib.h>
> #include "mat.h"
>

I don't see
#include "engine.h"

I'm not sure, but it might be needed for some of your code.

[James Tursa]

"Ben" wrote in message <jojd47$k7c$1...@newscl01ah.mathworks.com>...

engine.h would work since it includes matrix.h as a byproduct, but since I don't see any engine related functions in the code, what *will* be needed is matrix.h. You can get that by including engine.h or directly as:

#include "matrix.h"

The matrix.h file is needed in order to do all the mxArray manipulation.

James Tursa

[Ben]

<jojci3$he4$1...@newscl01ah.mathworks.com>...
> > > HI,
> > > I am trying to compile the following code, but am unsuccessful. I have not seen any documentation of using the mat.h file. Any suggestions would be great

What errors are you getting? Any more specifics you can offer?

[Jerome]

Thanks you! when I complied I received the following:
gcc -I/usr/local/include/ -L/usr/local/lib example2.c

example2.c:3:17: error: mat.h: No such file or directory
example2.c:4:20: error: engine.h: No such file or directory
example2.c: In function ‘diagnose’:
example2.c:6: error: ‘MATFile’ undeclared (first use in this function)
example2.c:6: error: (Each undeclared identifier is reported only once
example2.c:6: error: for each function it appears in.)
example2.c:6: error: ‘pmat’ undeclared (first use in this function)
example2.c:11: error: ‘mxArray’ undeclared (first use in this function)
example2.c:11: error: ‘pa’ undeclared (first use in this function)
example2.c:27: warning: cast to pointer from integer of different size




"Ben" wrote in message <jojfof$2mh$1...@newscl01ah.mathworks.com>...

[dpb]

On 5/11/2012 12:46 PM, Jerome wrote:
> Thanks you! when I complied I received the following:
> gcc -I/usr/local/include/ -L/usr/local/lib example2.c
> example2.c:3:17: error: mat.h: No such file or directory
> example2.c:4:20: error: engine.h: No such file or directory

...

The compiler didn't find the above header files--

--

[Jerome]

Thanks,
After locating the header files, I received the following error.
gcc -I/usr/local/MATLAB/R2012a/extern/include/ -L/usr/local/MATLAB/R2012/extern/lib example2.c -lm
/tmp/ccmBsgpB.o: In function `diagnose':
example2.c:(.text+0x32): undefined reference to `matOpen'
example2.c:(.text+0x73): undefined reference to `matGetDir'
example2.c:(.text+0xf3): undefined reference to `mxFree'
example2.c:(.text+0xff): undefined reference to `matClose'
example2.c:(.text+0x137): undefined reference to `matOpen'
example2.c:(.text+0x18e): undefined reference to `matGetNextVariableInfo'
example2.c:(.text+0x1c8): undefined reference to `mxGetNumberOfDimensions'
example2.c:(.text+0x1f0): undefined reference to `mxIsFromGlobalWS'
example2.c:(.text+0x216): undefined reference to `mxDestroyArray'
example2.c:(.text+0x232): undefined reference to `matClose'
example2.c:(.text+0x26a): undefined reference to `matOpen'
example2.c:(.text+0x2c1): undefined reference to `matGetNextVariable'
example2.c:(.text+0x2fb): undefined reference to `mxGetNumberOfDimensions'
example2.c:(.text+0x323): undefined reference to `mxIsFromGlobalWS'
example2.c:(.text+0x349): undefined reference to `mxDestroyArray'
example2.c:(.text+0x365): undefined reference to `matClose'
collect2: ld returned 1 exit status

Thanks!
dpb <no...@non.net> wrote in message <jojlor$n7e$1...@speranza.aioe.org>...

[dpb]

On 5/11/2012 1:52 PM, Jerome wrote:

...don't toppost...

> Thanks,
> After locating the header files, I received the following error.

...

> example2.c:(.text+0x32): undefined reference to `matOpen'

...

well, now the linker needs to know where the librar(y|ies) is/are...

--

[Jerome]

dpb <no...@non.net> wrote in message <jojovd$vg0$1...@speranza.aioe.org>...

Thanks,
I can compile and link using mex instead of gcc but it gives a seg fault. This should not be. Any suggestions?

[dpb]

On 5/11/2012 2:52 PM, Jerome wrote:
> dpb <no...@non.net> wrote in message <jojovd$vg0$1...@speranza.aioe.org>...

...

> I can compile and link using mex instead of gcc but it gives a seg
> fault. This should not be. Any suggestions?

Then you're down to debugging...this generally means a bad pointer
somewhere--you've got a reference to a passed by value argument in place
of a by reference or vice versa, an array index 0 or out of bounds,
etc., etc., etc, ...

--