dscal.c

svm的实现源码

#include "blas.h"

int dscal_(int *n, double *sa, double *sx, int *incx)
{
  long i, m, nincx, nn, iincx;
  double ssa;

  /* scales a vector by a constant.   
     uses unrolled loops for increment equal to 1.   
     jack dongarra, linpack, 3/11/78.   
     modified 3/93 to return if incx .le. 0.   
     modified 12/3/93, array(1) declarations changed to array(*) */

  /* Dereference inputs */
  nn = *n;
  iincx = *incx;
  ssa = *sa;

  if (nn > 0 && iincx > 0)
  {
    if (iincx == 1) /* code for increment equal to 1 */
    {
      m = nn-4;
      for (i = 0; i < m; i += 5)
      {
        sx[i] = ssa * sx[i];
        sx[i+1] = ssa * sx[i+1];
        sx[i+2] = ssa * sx[i+2];
        sx[i+3] = ssa * sx[i+3];
        sx[i+4] = ssa * sx[i+4];
      }
      for ( ; i < nn; ++i) /* clean-up loop */
        sx[i] = ssa * sx[i];
    }
    else /* code for increment not equal to 1 */
    {
      nincx = nn * iincx;
      for (i = 0; i < nincx; i += iincx)
        sx[i] = ssa * sx[i];
    }
  }

  return 0;
} /* dscal_ */