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xzlarfg.cpp
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#include <cmath>
#include "rt_nonfinite.h"
#include "processedout.h"
#include "xzlarfg.h"
#include "xnrm2.h"
static double rt_hypotd_snf(double u0, double u1);
static double rt_hypotd_snf(double u0, double u1)
{
double y;
double a;
double b;
a = std::abs(u0);
b = std::abs(u1);
if (a < b) {
a /= b;
y = b * std::sqrt(a * a + 1.0);
} else if (a > b) {
b /= a;
y = a * std::sqrt(b * b + 1.0);
} else if (rtIsNaN(b)) {
y = b;
} else {
y = a * 1.4142135623730951;
}
return y;
}
double b_xzlarfg(int n, double *alpha1, double x[1080], int ix0)
{
double tau;
double xnorm;
int knt;
int i8;
int k;
tau = 0.0;
if (!(n <= 0)) {
xnorm = c_xnrm2(n - 1, x, ix0);
if (xnorm != 0.0) {
xnorm = rt_hypotd_snf(*alpha1, xnorm);
if (*alpha1 >= 0.0) {
xnorm = -xnorm;
}
if (std::abs(xnorm) < 1.0020841800044864E-292) {
knt = 0;
i8 = (ix0 + n) - 2;
do {
knt++;
for (k = ix0; k <= i8; k++) {
x[k - 1] *= 9.9792015476736E+291;
}
xnorm *= 9.9792015476736E+291;
*alpha1 *= 9.9792015476736E+291;
} while (!(std::abs(xnorm) >= 1.0020841800044864E-292));
xnorm = rt_hypotd_snf(*alpha1, c_xnrm2(n - 1, x, ix0));
if (*alpha1 >= 0.0) {
xnorm = -xnorm;
}
tau = (xnorm - *alpha1) / xnorm;
*alpha1 = 1.0 / (*alpha1 - xnorm);
i8 = (ix0 + n) - 2;
for (k = ix0; k <= i8; k++) {
x[k - 1] *= *alpha1;
}
for (k = 1; k <= knt; k++) {
xnorm *= 1.0020841800044864E-292;
}
*alpha1 = xnorm;
} else {
tau = (xnorm - *alpha1) / xnorm;
*alpha1 = 1.0 / (*alpha1 - xnorm);
i8 = (ix0 + n) - 2;
for (k = ix0; k <= i8; k++) {
x[k - 1] *= *alpha1;
}
*alpha1 = xnorm;
}
}
}
return tau;
}
double xzlarfg(int n, double *alpha1, emxArray_real_T *x, int ix0)
{
double tau;
double xnorm;
int knt;
int i4;
int k;
tau = 0.0;
if (!(n <= 0)) {
xnorm = xnrm2(n - 1, x, ix0);
if (xnorm != 0.0) {
xnorm = rt_hypotd_snf(*alpha1, xnorm);
if (*alpha1 >= 0.0) {
xnorm = -xnorm;
}
if (std::abs(xnorm) < 1.0020841800044864E-292) {
knt = 0;
i4 = (ix0 + n) - 2;
do {
knt++;
for (k = ix0; k <= i4; k++) {
x->data[k - 1] *= 9.9792015476736E+291;
}
xnorm *= 9.9792015476736E+291;
*alpha1 *= 9.9792015476736E+291;
} while (!(std::abs(xnorm) >= 1.0020841800044864E-292));
xnorm = rt_hypotd_snf(*alpha1, xnrm2(n - 1, x, ix0));
if (*alpha1 >= 0.0) {
xnorm = -xnorm;
}
tau = (xnorm - *alpha1) / xnorm;
*alpha1 = 1.0 / (*alpha1 - xnorm);
i4 = (ix0 + n) - 2;
for (k = ix0; k <= i4; k++) {
x->data[k - 1] *= *alpha1;
}
for (k = 1; k <= knt; k++) {
xnorm *= 1.0020841800044864E-292;
}
*alpha1 = xnorm;
} else {
tau = (xnorm - *alpha1) / xnorm;
*alpha1 = 1.0 / (*alpha1 - xnorm);
i4 = (ix0 + n) - 2;
for (k = ix0; k <= i4; k++) {
x->data[k - 1] *= *alpha1;
}
*alpha1 = xnorm;
}
}
}
return tau;
}