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  • 2022.1
  • 12/20/2021
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CHEEV Example Program in C

/******************************************************************************* * Copyright (C) 2009-2015 Intel Corporation. All Rights Reserved. * The information and material ("Material") provided below is owned by Intel * Corporation or its suppliers or licensors, and title to such Material remains * with Intel Corporation or its suppliers or licensors. The Material contains * proprietary information of Intel or its suppliers and licensors. The Material * is protected by worldwide copyright laws and treaty provisions. No part of * the Material may be copied, reproduced, published, uploaded, posted, * transmitted, or distributed in any way without Intel's prior express written * permission. No license under any patent, copyright or other intellectual * property rights in the Material is granted to or conferred upon you, either * expressly, by implication, inducement, estoppel or otherwise. Any license * under such intellectual property rights must be express and approved by Intel * in writing. * ******************************************************************************** */ /* CHEEV Example. ============== Program computes all eigenvalues and eigenvectors of a complex Hermitian matrix A: ( 9.14, 0.00) ( -4.37, -9.22) ( -1.98, -1.72) ( -8.96, -9.50) ( -4.37, 9.22) ( -3.35, 0.00) ( 2.25, -9.51) ( 2.57, 2.40) ( -1.98, 1.72) ( 2.25, 9.51) ( -4.82, 0.00) ( -3.24, 2.04) ( -8.96, 9.50) ( 2.57, -2.40) ( -3.24, -2.04) ( 8.44, 0.00) Description. ============ The routine computes all eigenvalues and, optionally, eigenvectors of an n-by-n complex Hermitian matrix A. The eigenvector v(j) of A satisfies A*v(j) = lambda(j)*v(j) where lambda(j) is its eigenvalue. The computed eigenvectors are orthonormal. Example Program Results. ======================== CHEEV Example Program Results Eigenvalues -16.00 -6.76 6.67 25.51 Eigenvectors (stored columnwise) ( 0.34, 0.00) ( -0.55, 0.00) ( 0.31, 0.00) ( -0.70, 0.00) ( 0.44, -0.54) ( 0.26, 0.18) ( 0.45, 0.29) ( 0.22, -0.28) ( -0.48, -0.37) ( -0.52, -0.02) ( -0.05, 0.57) ( 0.15, 0.08) ( 0.10, -0.12) ( -0.50, 0.28) ( -0.23, -0.48) ( 0.34, -0.49) */ #include <stdlib.h> #include <stdio.h> /* Complex datatype */ struct _fcomplex { float re, im; }; typedef struct _fcomplex fcomplex; /* CHEEV prototype */ extern void cheev( char* jobz, char* uplo, int* n, fcomplex* a, int* lda, float* w, fcomplex* work, int* lwork, float* rwork, int* info ); /* Auxiliary routines prototypes */ extern void print_matrix( char* desc, int m, int n, fcomplex* a, int lda ); extern void print_rmatrix( char* desc, int m, int n, float* a, int lda ); /* Parameters */ #define N 4 #define LDA N /* Main program */ int main() { /* Locals */ int n = N, lda = LDA, info, lwork; fcomplex wkopt; fcomplex* work; /* Local arrays */ /* rwork dimension should be at least max(1,3*n-2) */ float w[N], rwork[3*N-2]; fcomplex a[LDA*N] = { { 9.14f, 0.00f}, {-4.37f, 9.22f}, {-1.98f, 1.72f}, {-8.96f, 9.50f}, { 0.00f, 0.00f}, {-3.35f, 0.00f}, { 2.25f, 9.51f}, { 2.57f, -2.40f}, { 0.00f, 0.00f}, { 0.00f, 0.00f}, {-4.82f, 0.00f}, {-3.24f, -2.04f}, { 0.00f, 0.00f}, { 0.00f, 0.00f}, { 0.00f, 0.00f}, { 8.44f, 0.00f} }; /* Executable statements */ printf( " CHEEV Example Program Results\n" ); /* Query and allocate the optimal workspace */ lwork = -1; cheev( "Vectors", "Lower", &n, a, &lda, w, &wkopt, &lwork, rwork, &info ); lwork = (int)wkopt.re; work = (fcomplex*)malloc( lwork*sizeof(fcomplex) ); /* Solve eigenproblem */ cheev( "Vectors", "Lower", &n, a, &lda, w, work, &lwork, rwork, &info ); /* Check for convergence */ if( info > 0 ) { printf( "The algorithm failed to compute eigenvalues.\n" ); exit( 1 ); } /* Print eigenvalues */ print_rmatrix( "Eigenvalues", 1, n, w, 1 ); /* Print eigenvectors */ print_matrix( "Eigenvectors (stored columnwise)", n, n, a, lda ); /* Free workspace */ free( (void*)work ); exit( 0 ); } /* End of CHEEV Example */ /* Auxiliary routine: printing a matrix */ void print_matrix( char* desc, int m, int n, fcomplex* a, int lda ) { 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].re, a[i+j*lda].im ); printf( "\n" ); } } /* Auxiliary routine: printing a real matrix */ void print_rmatrix( char* desc, int m, int n, float* a, int lda ) { int i, j; printf( "\n %s\n", desc ); for( i = 0; i < m; i++ ) { for( j = 0; j < n; j++ ) printf( " %6.2f", a[i+j*lda] ); printf( "\n" ); } }

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