22 lines
420 B
Java
22 lines
420 B
Java
package btools.util;
|
|
|
|
/**
|
|
* Some fast approximations to mathematical functions
|
|
*
|
|
* @author ab
|
|
*/
|
|
public class FastMath {
|
|
/**
|
|
* Approximation to Math.exp for small negative arguments
|
|
*/
|
|
public static double exp(double e) {
|
|
double x = e;
|
|
double f = 1.;
|
|
while (e < -1.) {
|
|
e += 1.;
|
|
f *= 0.367879;
|
|
}
|
|
return f * (1. + x * (1. + x * (0.5 + x * (0.166667 + 0.0416667 * x))));
|
|
}
|
|
}
|