On Tue, Mar 27, 2012 at 12:53:25PM +0200, "Detlef Günther" wrote:
> Hi Thomas,
>
> congrace may be used by writing a wrapper "Expression" to UnivarteFunction:
>
>
> import org.apache.commons.math3.analysis.UnivariateFunction;
>
> import de.congrace.exp4j.Calculable;
> import de.congrace.exp4j.ExpressionBuilder;
>
> public class Expression implements UnivariateFunction {
> private Calculable calc = null;
>
> public Expression(String function) throws Exception {
> calc = new
> ExpressionBuilder(function).withVariableNames("x").build();
> }
>
> public double value(double x) {
> calc.setVariable("x", x);
> return calc.calculate();
> }
>
> }
>
> Using this you get the folowing code:
>
> final double relativeAccuracy = 1.0e-10;
> final double absoluteAccuracy = 1.0e-10;
> UnivariateSolver solver = new RegulaFalsiSolver(relativeAccuracy,
> absoluteAccuracy);
> Expression exp = new Expression("sin(3*x)");
> double root = solver.solve(99999, exp, 9.4, 9.7);
> System.out.println("root is " + root + " / " + exp.value(root));
>
> with output:
>
> root is 9.42477796076938 / 1.102182119232618E-15 (= 3*PI)
>
> ==> Interpreter may be integrated in commons/math, the same result as my
> interpreter.
The above shows a fine _use_ of Commons Math. What added value would there
be from integrating it into Commons Math?
> [...]
Gilles
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