NormDist.java

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   this work for additional information regarding copyright ownership.
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package org.apache.poi.ss.formula.functions;

import org.apache.commons.math3.distribution.NormalDistribution;
import org.apache.poi.ss.formula.OperationEvaluationContext;
import org.apache.poi.ss.formula.eval.ErrorEval;
import org.apache.poi.ss.formula.eval.EvaluationException;
import org.apache.poi.ss.formula.eval.NumberEval;
import org.apache.poi.ss.formula.eval.OperandResolver;
import org.apache.poi.ss.formula.eval.ValueEval;

/**
 * Implementation for Excel NORMDIST() and NORM.DIST() functions.
 * <ul>
 *   <li>https://support.microsoft.com/en-us/office/normdist-function-126db625-c53e-4591-9a22-c9ff422d6d58</li>
 *   <li>https://support.microsoft.com/en-us/office/norm-dist-function-edb1cc14-a21c-4e53-839d-8082074c9f8d</li>
 * </ul>
 */
public final class NormDist extends Fixed4ArgFunction implements FreeRefFunction {

    public static final NormDist instance = new NormDist();

    static double probability(double x, double mean, double stdev, boolean cumulative) {
        NormalDistribution normalDistribution = new NormalDistribution(mean, stdev);
        return cumulative ? normalDistribution.cumulativeProbability(x) : normalDistribution.density(x);
    }

    private NormDist() {}

    @Override
    public ValueEval evaluate(int srcRowIndex, int srcColumnIndex, ValueEval arg1, ValueEval arg2,
                              ValueEval arg3, ValueEval arg4) {
        try {
            Double xval = evaluateValue(arg1, srcRowIndex, srcColumnIndex);
            if (xval == null) {
                return ErrorEval.VALUE_INVALID;
            }
            Double mean = evaluateValue(arg2, srcRowIndex, srcColumnIndex);
            if (mean == null) {
                return ErrorEval.VALUE_INVALID;
            }
            Double stdev = evaluateValue(arg3, srcRowIndex, srcColumnIndex);
            if (stdev == null) {
                return ErrorEval.VALUE_INVALID;
            } else if (stdev.doubleValue() <= 0) {
                return ErrorEval.NUM_ERROR;
            }
            Boolean cumulative = OperandResolver.coerceValueToBoolean(arg4, false);
            if (cumulative == null) {
                return ErrorEval.VALUE_INVALID;
            }

            return new NumberEval(probability(
                    xval.doubleValue(), mean.doubleValue(), stdev.doubleValue(), cumulative.booleanValue()));
        } catch (EvaluationException e) {
            return e.getErrorEval();
        }
    }

    @Override
    public ValueEval evaluate(ValueEval[] args, OperationEvaluationContext ec) {
        if (args.length == 4) {
            return evaluate(ec.getRowIndex(), ec.getColumnIndex(), args[0], args[1], args[2], args[3]);
        }

        return ErrorEval.VALUE_INVALID;
    }

    private static Double evaluateValue(ValueEval arg, int srcRowIndex, int srcColumnIndex) throws EvaluationException {
        ValueEval veText = OperandResolver.getSingleValue(arg, srcRowIndex, srcColumnIndex);
        String strText1 = OperandResolver.coerceValueToString(veText);
        return OperandResolver.parseDouble(strText1);
    }
}