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/*
* Copyright (C) 2009, 2010 Nick Johnson <nickbjohnson4224 at gmail.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <apps/math.h>
#include <float.h>
float logf(float x) {
float y, y_old, ey, epsilon;
y = 0.0;
y_old = 1.0;
epsilon = FLT_EPSILON;
while (y > y_old + epsilon || y < y_old - epsilon) {
y_old = y;
ey = exp(y);
y -= (ey - x) / ey;
if (y > 700.0) {
y = 700.0;
}
if (y < -700.0) {
y = -700.0;
}
epsilon = (fabs(y) > 1.0) ? fabs(y) * FLT_EPSILON : FLT_EPSILON;
}
if (y == 700.0) {
return INFINITY;
}
if (y == -700.0) {
return INFINITY;
}
return y;
}
double log(double x) {
double y, y_old, ey, epsilon;
y = 0.0;
y_old = 1.0;
epsilon = DBL_EPSILON;
while (y > y_old + epsilon || y < y_old - epsilon) {
y_old = y;
ey = exp(y);
y -= (ey - x) / ey;
if (y > 700.0) {
y = 700.0;
}
if (y < -700.0) {
y = -700.0;
}
epsilon = (fabs(y) > 1.0) ? fabs(y) * DBL_EPSILON : DBL_EPSILON;
}
if (y == 700.0) {
return INFINITY;
}
if (y == -700.0) {
return INFINITY;
}
return y;
}
long double logl(long double x) {
long double y, y_old, ey, epsilon;
y = 0.0;
y_old = 1.0;
epsilon = 1e-6; //fixme
while (y > y_old + epsilon || y < y_old - epsilon) {
y_old = y;
ey = expl(y);
y -= (ey - x) / ey;
if (y > 700.0) {
y = 700.0;
}
if (y < -700.0) {
y = -700.0;
}
}
if (y == 700.0) {
return INFINITY;
}
if (y == -700.0) {
return INFINITY;
}
return y;
}
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