Mega Code Archive
Class for float-point calculations in J2ME applications CLDC
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/*
* Float11.java
*
* Copyright (C) 2005-2008 Tommi Laukkanen
* http://www.substanceofcode.com
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
//package com.substanceofcode.util;
/**
* <p>
* Title: Class for float-point calculations in J2ME applications CLDC 1.1
* </p>
* <p>
* Description: Useful methods for float-point calculations which absent in
* native Math class
* </p>
* <p>
* Copyright: Copyright (c) 2004 Nick Henson
* </p>
* <p>
* Company: UNTEH
* </p>
* <p>
* License: Free use only for non-commercial purpose
* </p>
* <p>
* If you want to use all or part of this class for commercial applications then
* take into account these conditions:
* </p>
* <p>
* 1. I need a one copy of your product which includes my class with license key
* and so on
* </p>
* <p>
* 2. Please append my copyright information henson.midp.Float (C) by Nikolay
* Klimchuk on ‘About’ screen of your product
* </p>
* <p>
* 3. If you have web site please append link <a
* href=â€http://henson.newmail.ruâ€>Nikolay Klimchuk</a> on the page with
* description of your product
* </p>
* <p>
* That's all, thank you!
* </p>
*
* @author Nikolay Klimchuk http://henson.newmail.ru
* @version 0.51
*/
public class Float11 {
/** Square root from 3 */
final static public double SQRT3 = 1.732050807568877294;
/** Log10 constant */
final static public double LOG10 = 2.302585092994045684;
/** ln(0.5) constant */
final static public double LOGdiv2 = -0.6931471805599453094;
//
static public double acos(double x) {
double f = asin(x);
if (f == Double.NaN)
return f;
return Math.PI / 2 - f;
}
static public double asin(double x) {
if (x < -1. || x > 1.)
return Double.NaN;
if (x == -1.)
return -Math.PI / 2;
if (x == 1)
return Math.PI / 2;
return atan(x / Math.sqrt(1 - x * x));
}
static public double atan(double x) {
boolean signChange = false;
boolean Invert = false;
int sp = 0;
double x2, a;
// check up the sign change
if (x < 0.) {
x = -x;
signChange = true;
}
// check up the invertation
if (x > 1.) {
x = 1 / x;
Invert = true;
}
// process shrinking the domain until x<PI/12
while (x > Math.PI / 12) {
sp++;
a = x + SQRT3;
a = 1 / a;
x = x * SQRT3;
x = x - 1;
x = x * a;
}
// calculation core
x2 = x * x;
a = x2 + 1.4087812;
a = 0.55913709 / a;
a = a + 0.60310579;
a = a - (x2 * 0.05160454);
a = a * x;
// process until sp=0
while (sp > 0) {
a = a + Math.PI / 6;
sp--;
}
// invertation took place
if (Invert)
a = Math.PI / 2 - a;
// sign change took place
if (signChange)
a = -a;
//
return a;
}
static public double atan2(double y, double x) {
// if x=y=0
if (y == 0. && x == 0.)
return 0.;
// if x>0 atan(y/x)
if (x > 0.)
return atan(y / x);
// if x<0 sign(y)*(pi - atan(|y/x|))
if (x < 0.) {
if (y < 0.)
return -(Math.PI - atan(y / x));
else
return Math.PI - atan(-y / x);
}
// if x=0 y!=0 sign(y)*pi/2
if (y < 0.)
return -Math.PI / 2.;
else
return Math.PI / 2.;
}
static public double exp(double x) {
if (x == 0.)
return 1.;
//
double f = 1;
long d = 1;
double k;
boolean isless = (x < 0.);
if (isless)
x = -x;
k = x / d;
//
for (long i = 2; i < 50; i++) {
f = f + k;
k = k * x / i;
}
//
if (isless)
return 1 / f;
else
return f;
}
static private double _log(double x) {
if (!(x > 0.))
return Double.NaN;
//
double f = 0.0;
//
int appendix = 0;
while (x > 0.0 && x <= 1.0) {
x *= 2.0;
appendix++;
}
//
x /= 2.0;
appendix--;
//
double y1 = x - 1.;
double y2 = x + 1.;
double y = y1 / y2;
//
double k = y;
y2 = k * y;
//
for (long i = 1; i < 50; i += 2) {
f += k / i;
k *= y2;
}
//
f *= 2.0;
for (int i = 0; i < appendix; i++)
f += LOGdiv2;
//
return f;
}
static public double log(double x) {
if (!(x > 0.))
return Double.NaN;
//
if (x == 1.0)
return 0.0;
// Argument of _log must be (0; 1]
if (x > 1.) {
x = 1 / x;
return -_log(x);
}
//
return _log(x);
}
static public double log10(double x) {
return log(x) / LOG10;
}
/*
* static public double log10(double x) { if(!(x>0.)) return Double.NaN; //
* boolean neg=false; if(x<0) { neg=true; x=-x; } // int index=0; if(x>1.) {
* // Great 1 while(x>1.) { x=x/10; index++; } } else { // Less 1
* while(x<1.) { x=x*10.; index--; } } // double res=index; if(x!=1.)
* res=res+(log(x)/LOG10); // if(neg) return 1./res; else return res; }
*/
static public double pow(double x, double y) {
if (y == 0.)
return 1.;
if (y == 1.)
return x;
if (x == 0.)
return 0.;
if (x == 1.)
return 1.;
//
long l = (long) Math.floor(y);
boolean integerValue = (y == (double) l);
//
if (integerValue) {
boolean neg = false;
if (y < 0.)
neg = true;
//
double result = x;
for (long i = 1; i < (neg ? -l : l); i++)
result = result * x;
//
if (neg)
return 1. / result;
else
return result;
} else {
if (x > 0.)
return exp(y * log(x));
else
return Double.NaN;
}
}
}
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