SGGLSE called from a C interface throws a segmentation fault

[ykhalak]

Hi. I'm trying to call SGGLSE from within C code (modification to the GROMACS package), but it keeps throwing a segmentation fault after entering this function:

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Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff125f700 (LWP 10323)]
0x00007ffff5f5c583 in sgglse_ () from /usr/lib64/liblapack.so.3


Here is how I'm calling it:

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  float A[8]={1,1,1,1, 1,3,-1,1, 1,1,1,1};
  float c[4]={1,2,3,4};
  float B[2]={1,1, 1,1, 1,-1};
  float d[1]={7,4};
  float x[3];
  int lwork, info;
  lwork=9;
  real work[lwork];
 
  F77_FUNC(sgglse, SGGLSE) (4,
       3, 2, &A, 2, &B, 1,
       &c, &d, &x, &work, lwork, &info);


This is based on a test case I found in http://www.netlib.org/utk/people/JackDo ... K-2005.pdf
The F77_FUNC is a macro that works without problems in other parts of the GROMACS code to call LAPACK functions.
The LAPACK version I'm using is lapack-devel 3.4.1-4.1.2-x86_64 from the OpenSuse 12.2 repository.
I even tried to build LAPACK from source with the debug flag (-g), but couldn't get cmake from the GROMACS code I'm working with to find it as no .so file was produced.

Any help tracing down this segmentation fault would be greatly appreciated.

[admin]

Your matrices are the wrong size, and contain wrong data.
Below is a code that works fine (using LAPACKE - The C Standard Interface to LAPACK - included in the LAPACK package)

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#include  <stdio.h>
#include <lapacke.h>

int main()
{
  float A[12]={1,1,1,
               1,3,1,
               1,-1,1,
               1,1,1};
  float c[4]={1,2,3,4};
  float B[6]={1,1, 1,
              1, 1,-1};
  float d[2]={7,4};
  float x[3];
  lapack_int lwork, info;
  lwork=9;
  float work[lwork];
 
//CALL SGGLSE( M, N, P, A, LDA, B, LDB, C, D, X, WORK, LWORK, INFO ) 
info = LAPACKE_sgglse(LAPACK_ROW_MAJOR,
      4, 3, 2, A, 3 ,B, 3, c, d, x);

if (info ==0)
{
   printf ("Solution: \n");
   for (int i=0; i<3; i++) printf("%f ",x[i]);
   printf("\n");
}

return(info);
}


Makefile

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LIBS=-L/Users/julie/opt/mylib -llapacke -llapack -lrefcblas -lrefblas
IDIR =/Users/julie/opt/mylib
CC=gcc
CFLAGS=-I$(IDIR)
DEPS = lapacke.h
OBJ = prog.o

%.o: %.c $(DEPS)
   $(CC) -c -o $@ $< $(CFLAGS)

prog.exe: $(OBJ)
   gfortran -o $@ $^ $(CFLAGS) $(LIBS)

run : prog.exe
   ./prog.exe
   
clean:
   rm -f *.o *.exe *~ core

I strongly advice you to use LAPACKE to call LAPACK from C.
Hope it helps
Julie