47 lines
1.3 KiB
Java
47 lines
1.3 KiB
Java
package com.maths;
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/**
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* Class for linear convolution of two discrete signals
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*
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* @author Ioannis Karavitsis
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* @version 1.0
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* */
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public class Convolution
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{
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/**
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* Discrete linear convolution function. Both input signals and the output signal must start from 0.
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* If you have a signal that has values before 0 then shift it to start from 0.
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*
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* @param A The first discrete signal
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* @param B The second discrete signal
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* @return The convolved signal
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* */
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public static double[] convolution(double[] A, double[] B)
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{
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double[] convolved = new double[A.length + B.length - 1];
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/*
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The discrete convolution of two signals A and B is defined as:
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A.length
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C[i] = Σ (A[k]*B[i-k])
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k=0
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It's obvious that: 0 <= k <= A.length , 0 <= i <= A.length + B.length - 2 and 0 <= i-k <= B.length - 1
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From the last inequality we get that: i - B.length + 1 <= k <= i and thus we get the conditions below.
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*/
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for(int i = 0; i < convolved.length; i++)
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{
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convolved[i] = 0;
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int k = Math.max(i - B.length + 1, 0);
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while(k < i + 1 && k < A.length)
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{
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convolved[i] += A[k] * B[i - k];
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k++;
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}
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}
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return convolved;
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}
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} |