150 lines
5.1 KiB
C
150 lines
5.1 KiB
C
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/* MDH WCET BENCHMARK SUITE. File version $Id: ludcmp.c,v 1.2 2006/01/27 13:15:28 jgn Exp $ */
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/*************************************************************************/
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/* */
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/* SNU-RT Benchmark Suite for Worst Case Timing Analysis */
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/* ===================================================== */
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/* Collected and Modified by S.-S. Lim */
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/* sslim@archi.snu.ac.kr */
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/* Real-Time Research Group */
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/* Seoul National University */
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/* */
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/* */
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/* < Features > - restrictions for our experimental environment */
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/* */
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/* 1. Completely structured. */
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/* - There are no unconditional jumps. */
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/* - There are no exit from loop bodies. */
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/* (There are no 'break' or 'return' in loop bodies) */
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/* 2. No 'switch' statements. */
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/* 3. No 'do..while' statements. */
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/* 4. Expressions are restricted. */
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/* - There are no multiple expressions joined by 'or', */
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/* 'and' operations. */
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/* 5. No library calls. */
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/* - All the functions needed are implemented in the */
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/* source file. */
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/* */
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/* */
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/*************************************************************************/
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/* */
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/* FILE: ludcmp.c */
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/* SOURCE : Turbo C Programming for Engineering */
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/* */
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/* DESCRIPTION : */
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/* */
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/* Simultaneous linear equations by LU decomposition. */
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/* The arrays a[][] and b[] are input and the array x[] is output */
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/* row vector. */
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/* The variable n is the number of equations. */
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/* The input arrays are initialized in function main. */
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/* */
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/* */
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/* REMARK : */
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/* */
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/* EXECUTION TIME : */
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/* */
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/* */
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/*************************************************************************/
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/* Changes:
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* JG 2005/12/12: Indented program. Removed unused variable nmax.
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*/
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/*
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** Benchmark Suite for Real-Time Applications, by Sung-Soo Lim
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**
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** III-4. ludcmp.c : Simultaneous Linear Equations by LU Decomposition
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** (from the book C Programming for EEs by Hyun Soon Ahn)
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*/
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double a[50][50], b[50], x[50];
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int ludcmp( /* int nmax, */ int n, double eps);
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static double
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fabs(double n)
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{
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double f;
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if (n >= 0)
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f = n;
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else
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f = -n;
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return f;
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}
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int
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main(void)
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{
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int i, j/*, nmax = 50*/, n = 5, chkerr;
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double eps, w;
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eps = 1.0e-6;
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for (i = 0; i <= n; i++) {
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w = 0.0;
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for (j = 0; j <= n; j++) {
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a[i][j] = (i + 1) + (j + 1);
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if (i == j)
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a[i][j] *= 10.0;
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w += a[i][j];
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}
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b[i] = w;
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}
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chkerr = ludcmp( /* nmax, */ n, eps);
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return 0;
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}
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int
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ludcmp( /* int nmax, */ int n, double eps)
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{
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int i, j, k;
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double w, y[100];
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if (n > 99 || eps <= 0.0)
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return (999);
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for (i = 0; i < n; i++) {
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if (fabs(a[i][i]) <= eps)
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return (1);
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for (j = i + 1; j <= n; j++) {
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w = a[j][i];
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if (i != 0)
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for (k = 0; k < i; k++)
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w -= a[j][k] * a[k][i];
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a[j][i] = w / a[i][i];
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}
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for (j = i + 1; j <= n; j++) {
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w = a[i + 1][j];
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for (k = 0; k <= i; k++)
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w -= a[i + 1][k] * a[k][j];
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a[i + 1][j] = w;
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}
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}
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y[0] = b[0];
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for (i = 1; i <= n; i++) {
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w = b[i];
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for (j = 0; j < i; j++)
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w -= a[i][j] * y[j];
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y[i] = w;
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}
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x[n] = y[n] / a[n][n];
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for (i = n - 1; i >= 0; i--) {
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w = y[i];
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for (j = i + 1; j <= n; j++)
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w -= a[i][j] * x[j];
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x[i] = w / a[i][i];
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}
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return (0);
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}
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