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  • 12/20/2021
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LAPACKE_ssysv Example Program in C for Row Major Data Layout

/******************************************************************************* * 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. * ******************************************************************************** */ /* LAPACKE_ssysv Example. ====================== The program computes the solution to the system of linear equations with a real symmetric matrix A and multiple right-hand sides B, where A is the coefficient matrix: -5.86 3.99 -5.93 -2.82 7.69 3.99 4.46 2.58 4.42 4.61 -5.93 2.58 -8.52 8.57 7.69 -2.82 4.42 8.57 3.72 8.07 7.69 4.61 7.69 8.07 9.83 and B is the right-hand side matrix: 1.32 -6.33 -8.77 2.22 1.69 -8.33 0.12 -1.56 9.54 -6.41 -9.49 9.56 6.33 -3.67 7.48 Description. ============ The routine solves for X the real system of linear equations A*X = B, where A is an n-by-n symmetric 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*UT or A = L*D*LT , where U (or L) is a product of permutation and unit upper (lower) triangular matrices, and D is symmetric 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_ssysv (row-major, high-level) Example Program Results Solution 1.17 0.52 -0.86 -0.71 1.05 -4.90 -0.63 -0.52 0.99 -0.33 0.43 1.22 0.83 -1.22 1.96 Details of factorization -5.86 0.00 0.00 0.00 0.00 -0.68 7.18 0.00 0.00 0.00 1.01 -0.20 -2.82 0.00 0.00 0.48 0.35 11.93 4.21 0.00 -1.31 1.37 0.02 0.16 6.22 Pivot indices 1 2 -4 -4 5 */ #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, float* a, MKL_INT lda ); extern void print_int_vector( char* desc, MKL_INT n, MKL_INT* a ); /* Parameters */ #define N 5 #define NRHS 3 #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]; float a[LDA*N] = { -5.86f, 0.00f, 0.00f, 0.00f, 0.00f, 3.99f, 4.46f, 0.00f, 0.00f, 0.00f, -5.93f, 2.58f, -8.52f, 0.00f, 0.00f, -2.82f, 4.42f, 8.57f, 3.72f, 0.00f, 7.69f, 4.61f, 7.69f, 8.07f, 9.83f }; float b[LDB*N] = { 1.32f, -6.33f, -8.77f, 2.22f, 1.69f, -8.33f, 0.12f, -1.56f, 9.54f, -6.41f, -9.49f, 9.56f, 6.33f, -3.67f, 7.48f }; /* Executable statements */ printf( "LAPACKE_ssysv (row-major, high-level) Example Program Results\n" ); /* Solve the equations A*X = B */ info = LAPACKE_ssysv( LAPACK_ROW_MAJOR, 'L', 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_ssysv Example */ /* Auxiliary routine: printing a matrix */ void print_matrix( char* desc, MKL_INT m, MKL_INT n, float* 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", a[i*lda+j] ); 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" ); }

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