gftrunc.c

来自「Proakis《contemporarycommunication system」· C语言 代码 · 共 61 行

/* ============================================================================
 *           Syntax:  c = gftrunc(a, tp)
 *GFTRUNC Truncates redundant part of a GF(P) polynomial.
 *       C = BFTRUNC(A) removes the zero coefficient from the highest order
 *       terms from a GF(P) polynomial A. If the highest order term coefficient
 *       is a non-zero number, the output of this function equals the input.
 *       The resulted GF(P) polynomial C is the same as A with a shortened
 *       form.
 *
 *       The GF(P) polynomial A is in ascending order, i.e.,
 *         A = [a_0, a_1, a_2,..., a_(n-1), a_n] represents
 *         A(X) = a_0 + a_1 X + a_2 X^2 +...+ a_(n-1) X^(n-1) + a_n X^n
 *       a_i must be an element in GF(P).
 *
 *       See also GFADD, GFDIV, GFTUPLE
 * ============================================================================
 *     Original designed by Wes Wang,
 *     Jun Wu,     The Mathworks, Inc.
 *     Dec-12, 1995
 *
 *     Copyright (c) 1995-96 by The MAthWorks, Inc.
 *     All Rights Reserved
 *     $Revision: 1.1 $  $Date: 1996/04/01 18:14:41 $
 * ============================================================================
 */
#include <math.h>
#include "mex.h"
#include "gflib.c"
void mexFunction(int nlhs, Matrix *plhs[], int nrhs, Matrix *prhs[])
{
    int     len_a, len_tp, i;
    int     *paa, *Iwork;
    double  *pa, *pc;

    pa = mxGetPr(prhs[0]);
    len_a = mxGetN(prhs[0])*mxGetM(prhs[0]);
    if(nrhs > 1)
        len_tp = mxGetN(prhs[1])*mxGetM(prhs[1]);
    else
        len_tp = 0;

    paa = (int *)mxCalloc(len_a, sizeof(int));
    Iwork = (int *)mxCalloc(len_a, sizeof(int));    
    for (i=0; i < len_a; i++){
        if(pa[i] == -mexGetInf() )
            paa[i] = -Inf;
        else
            paa[i] = (int)pa[i];
    }
    
    gftrunc(paa, &len_a, len_tp, Iwork);
    pc = mxGetPr(plhs[0] = mxCreateFull(1, len_a, 0));
    for(i=0; i < len_a; i++){
        if( paa[i] == -Inf )
            pc[i] = -mexGetInf();
        else
            pc[i] = (double)paa[i];
	}
    return;
}