nom.bdezonia.zorbage.procedure.impl.Step Maven / Gradle / Ivy

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/*
 * Zorbage: an algebraic data hierarchy for use in numeric processing.
 *
 * Copyright (c) 2016-2021 Barry DeZonia All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 * 
 * Redistributions of source code must retain the above copyright notice, this list
 * of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice, this
 * list of conditions and the following disclaimer in the documentation and/or other
 * materials provided with the distribution.
 * 
 * Neither the name of the  nor the names of its contributors may
 * be used to endorse or promote products derived from this software without specific
 * prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL  BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */
package nom.bdezonia.zorbage.procedure.impl;

import nom.bdezonia.zorbage.procedure.Procedure2;
import nom.bdezonia.zorbage.algebra.Algebra;
import nom.bdezonia.zorbage.algebra.Ordered;
import nom.bdezonia.zorbage.algebra.Unity;

/**
 * 
 * @author Barry DeZonia
 *
 */
public class Step & Ordered & Unity, U>
	implements Procedure2
{
	private final T algebra;
	private final U zero;
	private final U one;
	private final U h0;
	
	/**
	 * Heaviside step function. 
	 * 
	 * @param algebra
	 * @param h0 The value to return if the input is 0. Common values
	 *   are 0, 1/2, and 1.
	 */
	public Step(T algebra, U h0) {
		this.algebra = algebra;
		this.zero = algebra.construct();
		this.h0 = algebra.construct();
		this.one = algebra.construct();
		algebra.unity().call(this.one);
		algebra.assign().call(h0, this.h0);
		if (algebra.isLess().call(h0, this.zero) || algebra.isGreater().call(h0, this.one))
			throw new IllegalArgumentException("step: h0 out of sensible range");
	}
	
	@Override
	public void call(U a, U b) {
		int s = algebra.signum().call(a);
		if (s < 0)
			algebra.assign().call(zero, b);
		else if (s > 0)
			algebra.assign().call(one, b);
		else
			algebra.assign().call(h0, b);
	}

}