Example usage for org.apache.commons.math3.analysis DifferentiableUnivariateFunction derivative

Introduction

In this page you can find the example usage for org.apache.commons.math3.analysis DifferentiableUnivariateFunction derivative.

Prototype

UnivariateFunction derivative();

Source Link

Document

Returns the derivative of the function

Usage

From source file:org.apache.solr.client.solrj.io.eval.DerivativeEvaluator.java

@Override
public Object doWork(Object value) throws IOException {
    if (null == value) {
        throw new IOException(String.format(Locale.ROOT,
                "Invalid expression %s - null found for the first value", toExpression(constructingFactory)));
    }/*from w  ww . j  a  v a 2  s .c o  m*/

    if (!(value instanceof VectorFunction)) {
        throw new IOException(String.format(Locale.ROOT,
                "Invalid expression %s - found type %s for the first value, expecting a FunctionVector",
                toExpression(constructingFactory), value.getClass().getSimpleName()));
    }

    VectorFunction vectorFunction = (VectorFunction) value;
    if (!(vectorFunction.getFunction() instanceof DifferentiableUnivariateFunction)) {
        throw new IOException("Cannot evaluate derivative from parameter.");
    }

    DifferentiableUnivariateFunction func = (DifferentiableUnivariateFunction) vectorFunction.getFunction();
    double[] x = (double[]) vectorFunction.getFromContext("x");
    UnivariateFunction derfunc = func.derivative();
    double[] dvalues = new double[x.length];
    for (int i = 0; i < x.length; i++) {
        dvalues[i] = derfunc.value(x[i]);
    }

    VectorFunction vf = new VectorFunction(derfunc, dvalues);
    vf.addToContext("x", x);
    vf.addToContext("y", vectorFunction.getFromContext("y"));

    return vf;
}

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