Weird bug in LAPACKE: LAPACKE_zheevx()

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Weird bug in LAPACKE: LAPACKE_zheevx()

Postby Boris_MV » Mon Jun 20, 2016 6:50 pm

Hi all, here is a description of a weird bug I have encountered when using LAPACKE function LAPACKE_zheevx(). Simple test code that calculates three out of four eigenvalues/vectors (the example from the Intel's website) works well and gives correct output. However, if I introduce declaration of any string in the source code (e.g. std::string OutputFIlename;), the compilation goes well but at execution I get segmentation error SIGSEGV !!!
First, I will list the code that works:

Code: Select all
#include <iostream>
#include <string>
#include <fstream> 
#include <cassert> 

#include <stdlib.h>
#include <stdio.h>
#include <complex>
#include <math.h>

#include "Headers_LAPACKE\lapacke.h"
#include "Headers_LAPACKE\lapacke_config.h"
#include "Headers_LAPACKE\lapacke_mangling.h"
#include "Headers_LAPACKE\lapacke_utils.h"

void print_matrix( char* desc, lapack_int m, lapack_int n, lapack_complex_double* a, lapack_int lda );

int main()
{
    std::cout << "Start..." << std::endl;
    //std::string fn_VALS;

    // --------------- LAPACKE --- define variables ----------------------------------------------------------------
    //

    // Define arguments for LAPACKE_zheevx() routine:
    int matrix_layout;  // = LAPACK_ROW_MAJOR or LAPACK_COL_MAJOR

    char jobz;          // It is ="V" to calculate EigenVECTORS and
                        // ="N" if you don't do it.

    char range;         // ="A" for ALL values (don't want this),
                        // ="V" for values in in the half-open interval (vl,vu],
                        // ="I" for EigenVALUES indexed from il through iu (this is what you want).

    char uplo;          // ="U" for Upper Triangle of the matrix, or
                        // ="L" for the Lower triangle of the matrix.

    lapack_int n;       // the order of matrix "a" to be diagonalized.

    lapack_complex_double* a;   // complex array of dimension (lda,n).
                                // On entry it is Hermitian matrix "a".
                                // uplo="U" means the leading n-by-n upper triangular part of "a" contain the upper triangular part of the Hermitial matrix to be diagonalized.
                                // uplo="L" means equivalent for the lower triangular part.
                                // On exit, this content is destroyed.

    lapack_int lda;     // leading dimension of "a": lda >= max(1,n).

    double    vl;         // taken into account only if range="V": vl<vu. Not referenced if range="I" or range="A".
    double    vu;         // taken into account only if range="V": vl<vu. Not referenced if range="I" or range="A".

    lapack_int il;      // taken into account only if range="I": il<iu. Indices in ascending order of SMALLEST EigenVALUE to be returned. Not referenced if range="v" or range="A".
    lapack_int iu;      // taken into account only if range="I": il<iu. Indices in ascending order of LARGEST EigenVALUE to be returned.  Not referenced if range="v" or range="A".

    double    abstol;     // The absolute error tolerance for EigenVALUES. If abstop =<0, then EPS*|T| is used. If you get info>0 (some eigenvalues did not converge) then try abstol=2*DLAMCH('S').
    lapack_int* m;      // total number of EigenVALUES found: 0 =< m =< n, If range="A" then m=n, if range="I" then m = iu-il+1.
    double* w;          // double precision array of dimension n. On normal exit, the first m elements contain the selected EigenVALUES in ASCENDING ORDER.
    lapack_complex_double* z; // double precision array of dimension (ldz, max(1,m)). If jobz="V" and info=0, the first m-columns of z contain normalized EigenVECTORS of a, corresponding to the selected EigenVALUES, with i-th column of z contains the Eigenvectro corresponding to w(i) eigenvalue.
    lapack_int ldz;     // leading dimension of array z. ldz>=1 and if jobz="V" then ldz >= max(1,n).

        // following are  used only with LAPACKE_zheevx_work() routine:.
        //lapack_complex_double* work;    // array of dimension max(1,lwork).
        //lapack_int lwork;               // lwork=-1 means workspace query. Othewise it has to be length of the array work: lwork=2*n for n>1, and lwork >=1 for N=<1.
        //double* rwork;                  // array dimension is 7*n;
        //lapack_int* iwork;              // array dimension is 5*n;

    lapack_int* ifail;  // jobz="V" and info=0: first m elemens of ifail are zero. jobz="V" and info>0: ifail contain indices of the eigenvectors that failed to converge.
    lapack_int info;    //info=0 means successful exit. info>0 means eigenvectors failed to converge, their indices are in ifail. info<0, info=-i means i-th argument had an illegal value.
    //
    // ------------------------------------------------------------------------------------------------------------

    matrix_layout = LAPACK_ROW_MAJOR;
    jobz = 'V'; vl = 0.0; vu =100.0;
    il = 1; iu=4; // are ignored now.
    range = 'V';
    uplo ='U';
    n = 4;
    lda = n;
    ldz = n;

    z = new lapack_complex_double [ldz*n];
    w = new double [n];
    a = new lapack_complex_double [lda*n];
    a[0] =lapack_complex_double{6.51,0.0}; a[1] =lapack_make_complex_double(-5.92, 9.53); a[2]=lapack_complex_double{-2.46,2.91}; a[3]=lapack_complex_double{8.84,3.21};
    a[4] =lapack_complex_double{0.0,0.0};  a[5] =lapack_make_complex_double(-1.73,0.0);   a[6]=lapack_complex_double{6.5,2.09};    a[7]=lapack_complex_double{1.32, 8.81};
    a[8] =lapack_complex_double{0.0,0.0};  a[9] =lapack_make_complex_double(0.0,0.0);     a[10]=lapack_complex_double{6.90,0.0};   a[11]=lapack_complex_double{-0.59,2.47};
    a[12]=lapack_complex_double{0.0,0.0};  a[13]=lapack_make_complex_double(0.0,0.0);     a[14]=lapack_complex_double{0.0,0.0};    a[15]=lapack_complex_double{-2.85,0.0};

    ifail = new lapack_int [n];
    abstol = -1;  // set default tolerance for calcuation of EigVals in the assigned interval.

    print_matrix( "Entry Matrix A:", n, n, a, lda );
    std::cout << std::endl;

    info = LAPACKE_zheevx(matrix_layout, jobz, range, uplo, n, a, lda,  vl,  vu,  il, iu,  abstol, m, w, z, ldz, ifail);

    if (info>0)
    {
        std::cout << "Error: ZHEEVX failed to compute eigenvalues/vectors.";
        exit(1);
    }
    std::cout << "info = " << info << std::endl;

    std::cout << "Number of eigvals found: " << *m << std::endl;
    for (int i_e =0; i_e<*m; i_e++)
    {
         std::cout << "Eigval. " << i_e << " is " << w[i_e] << std::endl;
    }

    print_matrix( "Selected EigVECTORS (column-wise):", n, n, z, ldz );
    std::cout << std::endl;


    std::cout << "Done :-) !!!" <<std::endl;

    return 0;
}


////////////////////////////////////////////////////////* Auxiliary routine: printing a matrix */
void print_matrix( char* desc, lapack_int m, lapack_int n, lapack_complex_double* a, lapack_int lda )
{
        lapack_int i, j;
        printf( "\n %s\n", desc );
        for( i = 0; i < m; i++ )
        {
            for( j = 0; j < n; j++ )
            {
                printf( " (%6.2f,%6.2f)", lapack_complex_double_real(a[i*lda+j]), lapack_complex_double_imag(a[i*lda+j]) );
            }
            printf( "\n" );
        }
}


Now, if in main() one removes the comment symbol (//) on line 2:
Code: Select all
//std::string fn_VALS;

then this line will become
Code: Select all
std::string fn_VALS;
.

With this change on line 2, although the compilation still goes well, at the execution time you will get a SEGMENTATION error!!!!

More info:

I am using Windows 7 Pro and Code::Blocks, the LAPACKE headers and dll's were downloaded on 6/15/2016.
From the console: Process returned -1073741819 (0xC0000005)
From the Call Stack window in Code::Blocks
.......... main() calls LAPACKE_zheevx() [lapacke.dll]
.......... LAPACKE_zheevx() calls LAPACKE_zheevx_work() [lapacke.dll]
.......... LAPACKE_zheevx_work() calls zheevx_() [lapack.dll]
This problem prevents me from saving to a file the calculated eigenvalues and eigenvectors, making the whole effort useless. Please help.
Boris_MV
 
Posts: 7
Joined: Fri Dec 19, 2014 9:39 pm

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