/*
* __ .__ .__ ._____.
* _/ |_ _______ __|__| ____ | | |__\_ |__ ______
* \ __\/ _ \ \/ / |/ ___\| | | || __ \ / ___/
* | | ( <_> > <| \ \___| |_| || \_\ \\___ \
* |__| \____/__/\_ \__|\___ >____/__||___ /____ >
* \/ \/ \/ \/
*
* Copyright (c) 2006-2011 Karsten Schmidt
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* http://creativecommons.org/licenses/LGPL/2.1/
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*/
package spimedb.util.math;
/**
* Implements the sigmoid interpolation function with adjustable curve sharpness
*/
public class SigmoidInterpolation implements InterpolateStrategy {
private float sharpness;
private float sharpPremult;
/**
* Initializes the s-curve with default sharpness = 2
*/
public SigmoidInterpolation() {
this(2f);
}
public SigmoidInterpolation(float s) {
setSharpness(s);
}
public float getSharpness() {
return sharpness;
}
public double interpolate(double a, double b, double f) {
f = 1.0 + Math.exp(-((f * 2 - 1) * sharpPremult));
return a + (b - a) / f;
}
public float interpolate(float a, float b, float f) {
f = (float) (1.0 + Math.exp(-((f * 2 - 1) * sharpPremult)));
return a + (b - a) / f;
}
private void setSharpness(float s) {
sharpness = s;
sharpPremult = 5 * s;
}
}