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LAPACKE_cgeev Example Program in C for Column Major Data Layout
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/*
LAPACKE_cgeev Example.
======================
Program computes the eigenvalues and left and right eigenvectors of a general
rectangular matrix A:
( -3.84, 2.25) ( -8.94, -4.75) ( 8.95, -6.53) ( -9.87, 4.82)
( -0.66, 0.83) ( -4.40, -3.82) ( -3.50, -4.26) ( -3.15, 7.36)
( -3.99, -4.73) ( -5.88, -6.60) ( -3.36, -0.40) ( -0.75, 5.23)
( 7.74, 4.18) ( 3.66, -7.53) ( 2.58, 3.60) ( 4.59, 5.41)
Description.
============
The routine computes for an n-by-n complex nonsymmetric matrix A, the
eigenvalues and, optionally, the left and/or right eigenvectors. The right
eigenvector v(j) of A satisfies
A*v(j)= lambda(j)*v(j)
where lambda(j) is its eigenvalue. The left eigenvector u(j) of A satisfies
u(j)H*A = lambda(j)*u(j)H
where u(j)H denotes the conjugate transpose of u(j). The computed
eigenvectors are normalized to have Euclidean norm equal to 1 and
largest component real.
Example Program Results.
========================
LAPACKE_cgeev (column-major, high-level) Example Program Results
Eigenvalues
( -9.43,-12.98) ( -3.44, 12.69) ( 0.11, -3.40) ( 5.76, 7.13)
Left eigenvectors
( 0.24, -0.18) ( 0.61, 0.00) ( -0.18, -0.33) ( 0.28, 0.09)
( 0.79, 0.00) ( -0.05, -0.27) ( 0.82, 0.00) ( -0.55, 0.16)
( 0.22, -0.27) ( -0.21, 0.53) ( -0.37, 0.15) ( 0.45, 0.09)
( -0.02, 0.41) ( 0.40, -0.24) ( 0.06, 0.12) ( 0.62, 0.00)
Right eigenvectors
( 0.43, 0.33) ( 0.83, 0.00) ( 0.60, 0.00) ( -0.31, 0.03)
( 0.51, -0.03) ( 0.08, -0.25) ( -0.40, -0.20) ( 0.04, 0.34)
( 0.62, 0.00) ( -0.25, 0.28) ( -0.09, -0.48) ( 0.36, 0.06)
( -0.23, 0.11) ( -0.10, -0.32) ( -0.43, 0.13) ( 0.81, 0.00)
*/
#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_Complex8* a, MKL_INT lda );
/* Parameters */
#define N 4
#define LDA N
#define LDVL N
#define LDVR N
/* Main program */
int main() {
/* Locals */
MKL_INT n = N, lda = LDA, ldvl = LDVL, ldvr = LDVR, info;
/* Local arrays */
MKL_Complex8 w[N], vl[LDVL*N], vr[LDVR*N];
MKL_Complex8 a[LDA*N] = {
{-3.84f, 2.25f}, {-0.66f, 0.83f}, {-3.99f, -4.73f}, { 7.74f, 4.18f},
{-8.94f, -4.75f}, {-4.40f, -3.82f}, {-5.88f, -6.60f}, { 3.66f, -7.53f},
{ 8.95f, -6.53f}, {-3.50f, -4.26f}, {-3.36f, -0.40f}, { 2.58f, 3.60f},
{-9.87f, 4.82f}, {-3.15f, 7.36f}, {-0.75f, 5.23f}, { 4.59f, 5.41f}
};
/* Executable statements */
printf( "LAPACKE_cgeev (column-major, high-level) Example Program Results\n" );
/* Solve eigenproblem */
info = LAPACKE_cgeev( LAPACK_COL_MAJOR, 'V', 'V', n, a, lda, w, vl,
ldvl, vr, ldvr );
/* Check for convergence */
if( info > 0 ) {
printf( "The algorithm failed to compute eigenvalues.\n" );
exit( 1 );
}
/* Print eigenvalues */
print_matrix( "Eigenvalues", 1, n, w, 1 );
/* Print left eigenvectors */
print_matrix( "Left eigenvectors", n, n, vl, ldvl );
/* Print right eigenvectors */
print_matrix( "Right eigenvectors", n, n, vr, ldvr );
exit( 0 );
} /* End of LAPACKE_cgeev Example */
/* Auxiliary routine: printing a matrix */
void print_matrix( char* desc, MKL_INT m, MKL_INT n, MKL_Complex8* 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+j*lda].real, a[i+j*lda].imag );
printf( "\n" );
}
}
Parent topic: CGEEV Example