RealWorldTest.java

package org.openlca.expressions;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;

import org.junit.Test;

public class RealWorldTest {

	private FormulaInterpreter interpreter = new FormulaInterpreter();

	@Test
	public void greatCircle() throws Exception {
		// great circle distance between Berlin and Brussels
		interpreter.bind("b_a", "52.52 * pi/180");
		interpreter.bind("l_a", "13.41 * pi/180");
		interpreter.bind("b_b", "50.85 * pi/180");
		interpreter.bind("l_b", "4.35 * pi/180");
		interpreter.bind("re", "6378");
		interpreter
				.bind("d",
						"re * arccos(sin(b_a) * sin(b_b) + cos(b_a) * cos(b_b) * cos(l_b-l_a))");
		double val = interpreter.eval("d");
		assertEquals(651.81, val, 0.01);
	}

	@Test
	public void boxMuller() throws Exception {
		// generate normal distributed random numbers from
		// uniform distributed random numbers
		interpreter.bind("z1",
				"sqrt(-2 * ln(random())) * sin(2 * pi * random())");
		interpreter.bind("z2",
				"sqrt(-2 * ln(random())) * sin(2 * pi * random())");
		double z1 = interpreter.eval("z1");
		double z2 = interpreter.eval("z2");
		assertTrue(z1 != z2);
	}

	@Test
	public void bandFilter() throws Exception {
		interpreter.bind("R_p", "1800");
		interpreter.bind("R_l", "1.2");
		interpreter.bind("g", "9.81");
		interpreter.bind("d_p", "10^-3");
		interpreter.bind("n_l", "1.8*10^-5");
		interpreter.bind("Ar", "(R_p-R_l) * R_l * g * d_p^3 / n_l^2");
		interpreter
				.bind("Re_p",
						"42.9*(1-0.4) * (sqrt(1 + 3.11*10^-4 * (0.4^3 / (1-0.4)^2) * Ar) - 1)");
		interpreter.bind("v_min", "1 * Re_p * n_l / (d_p * R_l)");
		assertEquals(0.44, interpreter.eval("v_min"), 0.01);
	}

}