com.expleague.ml.func.generic.WSumSigmoid Maven / Gradle / Ivy
package com.expleague.ml.func.generic;
import com.expleague.commons.math.FuncC1;
import com.expleague.commons.math.vectors.Vec;
import com.expleague.commons.math.vectors.VecTools;
/**
* User: solar
* Date: 26.05.15
* Time: 11:45
*/
public class WSumSigmoid extends FuncC1.Stub {
public final Vec weights;
public WSumSigmoid(Vec weights) {
this.weights = weights;
}
public Vec gradientTo(Vec x, Vec to) {
final double exp = Math.exp(-VecTools.multiply(x, weights));
final double value = exp / (1 + exp) / (1 + exp);
VecTools.assign(to, weights);
VecTools.scale(to, value);
return to;
}
@Override
public double value(Vec x) {
final double exp = Math.exp(-VecTools.multiply(x, weights));
return 1./(1. + exp);
}
@Override
public int dim() {
return -1;
}
}
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