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LAPACKE_zhesv Example Program in C for Row Major Data Layout
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/*
LAPACKE_zhesv Example.
======================
The program computes the solution to the system of linear equations
with a Hermitian matrix A and multiple right-hand sides B,
where A is the coefficient matrix:
( -2.90, 0.00) ( 0.31, 4.46) ( 9.66, -5.66) ( -2.28, 2.14)
( 0.31, -4.46) ( -7.93, 0.00) ( 9.55, -4.62) ( -3.51, 3.11)
( 9.66, 5.66) ( 9.55, 4.62) ( 0.30, 0.00) ( 9.33, -9.66)
( -2.28, -2.14) ( -3.51, -3.11) ( 9.33, 9.66) ( 2.40, 0.00)
and B is the right-hand side matrix:
( -5.69, -8.21) ( -2.83, 6.46)
( -3.57, 1.99) ( -7.64, 1.10)
( 8.42, -9.83) ( -2.33, -4.23)
( -5.00, 3.85) ( 6.48, -3.81)
Description.
============
The routine solves for X the complex system of linear equations A*X = B,
where A is an n-by-n Hermitian matrix, the columns of matrix B are
individual right-hand sides, and the columns of X are the corresponding
solutions.
The diagonal pivoting method is used to factor A as A = U*D*UH or
A = L*D*LH, where U (or L) is a product of permutation and unit upper
(lower) triangular matrices, and D is Hermitian and block diagonal with
1-by-1 and 2-by-2 diagonal blocks.
The factored form of A is then used to solve the system of equations A*X = B.
Example Program Results.
========================
LAPACKE_zhesv (row-major, high-level) Example Program Results
Solution
( 0.22, -0.95) ( -1.13, 0.18)
( -1.42, -1.30) ( 0.70, 1.13)
( -0.65, -0.40) ( 0.04, 0.07)
( -0.48, 1.35) ( 1.15, -0.27)
Details of factorization
( 3.17, 0.00) ( 7.32, 3.28) ( -0.36, 0.06) ( 0.20, -0.82)
( 0.00, 0.00) ( 0.03, 0.00) ( -0.48, 0.03) ( 0.25, -0.76)
( 0.00, 0.00) ( 0.00, 0.00) ( 0.30, 0.00) ( 9.33, -9.66)
( 0.00, 0.00) ( 0.00, 0.00) ( 0.00, 0.00) ( 2.40, 0.00)
Pivot indices
-1 -1 -3 -3
*/
#include <stdlib.h>
#include <stdio.h>
#include "mkl_lapacke.h"
/* Auxiliary routines prototypes */
extern void print_matrix( char* desc, MKL_INT m, MKL_INT n, MKL_Complex16* a, MKL_INT lda );
extern void print_int_vector( char* desc, MKL_INT n, MKL_INT* a );
/* Parameters */
#define N 4
#define NRHS 2
#define LDA N
#define LDB NRHS
/* Main program */
int main() {
/* Locals */
MKL_INT n = N, nrhs = NRHS, lda = LDA, ldb = LDB, info;
/* Local arrays */
MKL_INT ipiv[N];
MKL_Complex16 a[LDA*N] = {
{-2.90, 0.00}, { 0.31, 4.46}, { 9.66, -5.66}, {-2.28, 2.14},
{ 0.00, 0.00}, {-7.93, 0.00}, { 9.55, -4.62}, {-3.51, 3.11},
{ 0.00, 0.00}, { 0.00, 0.00}, { 0.30, 0.00}, { 9.33, -9.66},
{ 0.00, 0.00}, { 0.00, 0.00}, { 0.00, 0.00}, { 2.40, 0.00}
};
MKL_Complex16 b[LDB*N] = {
{-5.69, -8.21}, {-2.83, 6.46},
{-3.57, 1.99}, {-7.64, 1.10},
{ 8.42, -9.83}, {-2.33, -4.23},
{-5.00, 3.85}, { 6.48, -3.81}
};
/* Executable statements */
printf( "LAPACKE_zhesv (row-major, high-level) Example Program Results\n" );
/* Solve the equations A*X = B */
info = LAPACKE_zhesv( LAPACK_ROW_MAJOR, 'U', n, nrhs, a, lda, ipiv,
b, ldb );
/* Check for the exact singularity */
if( info > 0 ) {
printf( "The element of the diagonal factor " );
printf( "D(%i,%i) is zero, so that D is singular;\n", info, info );
printf( "the solution could not be computed.\n" );
exit( 1 );
}
/* Print solution */
print_matrix( "Solution", n, nrhs, b, ldb );
/* Print details of factorization */
print_matrix( "Details of factorization", n, n, a, lda );
/* Print pivot indices */
print_int_vector( "Pivot indices", n, ipiv );
exit( 0 );
} /* End of LAPACKE_zhesv Example */
/* Auxiliary routine: printing a matrix */
void print_matrix( char* desc, MKL_INT m, MKL_INT n, MKL_Complex16* a, MKL_INT lda ) {
MKL_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)", a[i*lda+j].real, a[i*lda+j].imag );
printf( "\n" );
}
}
/* Auxiliary routine: printing a vector of integers */
void print_int_vector( char* desc, MKL_INT n, MKL_INT* a ) {
MKL_INT j;
printf( "\n %s\n", desc );
for( j = 0; j < n; j++ ) printf( " %6i", a[j] );
printf( "\n" );
}
Parent topic: ZHESV Example