xnrm2.cpp

#include <cmath>
#include "rt_nonfinite.h"
#include "processedout.h"
#include "xnrm2.h"

double b_xnrm2(const double x[1080], int ix0)
{
  double y;
  double scale;
  int k;
  double absxk;
  double t;
  y = 0.0;
  scale = 3.3121686421112381E-170;
  for (k = ix0; k <= ix0 + 359; k++) {
    absxk = std::abs(x[k - 1]);
    if (absxk > scale) {
      t = scale / absxk;
      y = 1.0 + y * t * t;
      scale = absxk;
    } else {
      t = absxk / scale;
      y += t * t;
    }
  }

  return scale * std::sqrt(y);
}

double c_xnrm2(int n, const double x[1080], int ix0)
{
  double y;
  double scale;
  int kend;
  int k;
  double absxk;
  double t;
  y = 0.0;
  if (!(n < 1)) {
    if (n == 1) {
      y = std::abs(x[ix0 - 1]);
    } else {
      scale = 3.3121686421112381E-170;
      kend = (ix0 + n) - 1;
      for (k = ix0; k <= kend; k++) {
        absxk = std::abs(x[k - 1]);
        if (absxk > scale) {
          t = scale / absxk;
          y = 1.0 + y * t * t;
          scale = absxk;
        } else {
          t = absxk / scale;
          y += t * t;
        }
      }

      y = scale * std::sqrt(y);
    }
  }

  return y;
}

double xnrm2(int n, const emxArray_real_T *x, int ix0)
{
  double y;
  double scale;
  int kend;
  int k;
  double absxk;
  double t;
  y = 0.0;
  if (!(n < 1)) {
    if (n == 1) {
      y = std::abs(x->data[ix0 - 1]);
    } else {
      scale = 3.3121686421112381E-170;
      kend = (ix0 + n) - 1;
      for (k = ix0; k <= kend; k++) {
        absxk = std::abs(x->data[k - 1]);
        if (absxk > scale) {
          t = scale / absxk;
          y = 1.0 + y * t * t;
          scale = absxk;
        } else {
          t = absxk / scale;
          y += t * t;
        }
      }

      y = scale * std::sqrt(y);
    }
  }

  return y;
}