srot.c

Go to the documentation of this file.

/* applies a plane rotation
   May,23,1988             */
 
#include "arith.h"
 
srot(n,sx,isx,jsx,incx,sy,isy,jsy,incy,c,s)
MATRIX sx,sy;
REAL c,s;
int n,incx,incy,isx,jsx,isy,jsy;
{
    REAL stemp;
    int i,ix,iy;
 
    if(n <= 0)
        return;
 
    if((incx != 1) || (incy != 1)){
 
        /* code for unequal increments or equal increments
           not equal to 1 */
/*
        ix=1;
        iy=1;
        if(incx < 0)
            ix= (-n+1)*incx+1;
        if(incy < 0)
            iy= (-n+1)*incy+1;
        for(i=1; i<=n; i++){
            stemp= c*sx[ix]+s*sy[iy];
            sy[iy]= c*sy[iy]-s*sx[ix];
            sx[ix]= stemp;
            ix= ix+incx;
            iy= iy+incy;
        }
*/
        return;
    }
 
/* code for both increments equal to 1 */
 
    for(i=0; i<n; i++){
        stemp= c*sx[isx+i][jsx]+s*sy[isy+i][jsy];
        sy[isy+i][jsy]= c*sy[isy+i][jsy]-s*sx[isx+i][jsx];
        sx[isx+i][jsx]=stemp;
    }
 
    return;
}