ABACUS/src/MATRIX/eigsrt.cc

#include "ABACUS.h"

void ABACUS::eigsrt (Vect_DP& d, SQMat_DP& v)
{
  // This puts the eigenvalues in INCREASING order, not decreasing as in NR !

  int i, j, k;
  DP p;

  int n = d.size();
  for (i = 0; i < n-1; i++) {
    p = d[k=i];
    for (j = i; j < n; j++) {
      if (d[j] <= p) {
	p = d[k = j];
      }
    }
    if (k != i) {
      d[k] = d[i];
      d[i] = p;
      for (j = 0; j < n; j++) {
	p = v[j][i];
	v[j][i] = v[j][k];
	v[j][k] = p;
      }
    }
  }
}