dlange.c

最著名最快的分子模拟软件

#include<math.h>
#include<ctype.h>
#include "gmx_lapack.h"


double
F77_FUNC(dlange,DLANGE)(char *norm,
	int *m,
	int *n,
	double *a,
	int *lda,
	double *work)
{
  char ch=toupper(*norm);
  double dtemp,sum,max,val,scale;
  int i,j;

  switch(ch) {
  case 'M':
    max = 0.0;
    for(j=0;j<*n;j++)
      for(i=0;i<*m;i++) {
	dtemp = fabs(a[j*(*lda)+i]);
	if(dtemp>max)
	  max = dtemp;
      }
    val = max;
    break;

  case 'O':
  case '1':
    max = 0.0;
    for(j=0;j<*n;j++) {
      sum = 0.0;
      for(i=0;i<*m;i++) 
	sum += fabs(a[j*(*lda)+i]);
      if(sum>max)
	max = sum;
    }
    val = max;
    break;

  case 'I':
    for(i=0;i<*m;i++)
      work[i] = 0.0;
    for(j=0;j<*n;j++)
      for(i=0;i<*m;i++)
	work[i] += fabs(a[j*(*lda)+i]);
    max = 0;
    for(i=0;i<*m;i++)
      if(work[i]>max)
	max=work[i];
    val = max;
    break;

  case 'F':
  case 'E':
    scale = 0.0;
    sum   = 1.0;
    i = 1;
    for(j=0;j<*n;j++) 
      F77_FUNC(dlassq,DLASSQ)(m,&(a[j*(*lda)+0]),&i,&scale,&sum);
    val = scale*sqrt(sum);
    break;

  default:
    val = 0.0;
    break;
  }
  return val;
}