math_npe_4 (FuseFL)

실제 에러코드는 이와 같음.

    public double solve(final UnivariateRealFunction f, double min, double max, double initial)
            throws MaxIterationsExceededException, FunctionEvaluationException {
        return solve(min, max); (72)
    }

Faulty Code:

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.math.analysis.solvers;

import org.apache.commons.math.FunctionEvaluationException;
import org.apache.commons.math.MaxIterationsExceededException;
import org.apache.commons.math.analysis.UnivariateRealFunction;

/**
 * Implements the <a href="http://mathworld.wolfram.com/Bisection.html">
 * bisection algorithm</a> for finding zeros of univariate real functions.
 * <p>
 * The function should be continuous but not necessarily smooth.</p>
 *
 * @version $Revision$ $Date$
 */
public class BisectionSolver extends UnivariateRealSolverImpl {

    /**
     * Construct a solver for the given function.
     *
     * @param f function to solve.
     * @deprecated as of 2.0 the function to solve is passed as an argument
     * to the {@link #solve(UnivariateRealFunction, double, double)} or
     * {@link UnivariateRealSolverImpl#solve(UnivariateRealFunction, double, double, double)}
     * method.
     */
    @Deprecated
    public BisectionSolver(UnivariateRealFunction f) {
        super(f, 100, 1E-6);
    }

    /**
     * Construct a solver.
     *
     */
    public BisectionSolver() {
        super(100, 1E-6);
    }

    /** {@inheritDoc} */
    @Deprecated
    public double solve(double min, double max, double initial)
            throws MaxIterationsExceededException, FunctionEvaluationException {
        return solve(f, min, max);
    }

    /** {@inheritDoc} */
    @Deprecated
    public double solve(double min, double max)
            throws MaxIterationsExceededException, FunctionEvaluationException {
        return solve(f, min, max);
    }

    /** {@inheritDoc} */
    public double solve(final UnivariateRealFunction f, double min, double max, double initial)
            throws MaxIterationsExceededException, FunctionEvaluationException {
        return solve(min, max);
    }

    /** {@inheritDoc} */
    public double solve(final UnivariateRealFunction f, double min, double max)
            throws MaxIterationsExceededException, FunctionEvaluationException {

        clearResult();
        verifyInterval(min,max);
        double m;
        double fm;
        double fmin;

        int i = 0;
        while (i < maximalIterationCount) {
            m = UnivariateRealSolverUtils.midpoint(min, max);
            fmin = f.value(min);
            fm = f.value(m);

            if (fm * fmin > 0.0) {
                // max and m bracket the root.
                min = m;
            } else {
                // min and m bracket the root.
                max = m;
            }

            if (Math.abs(max - min) <= absoluteAccuracy) {
                m = UnivariateRealSolverUtils.midpoint(min, max);
                setResult(m, i);
                return m;
            }
            ++i;
        }

        throw new MaxIterationsExceededException(maximalIterationCount);
    }
}

Task Description:

The provided code is an implementation of a bisection algorithm for finding zeros of univariate real functions in Java. Here’s a brief description:

This code is part of the Apache Commons Math library and resides in the org.apache.commons.math.analysis.solvers package. The BisectionSolver class extends the UnivariateRealSolverImpl class and implements the bisection method for solving univariate real functions.

Key Points:
Class License and Package Declaration:

The code is licensed under the Apache License, Version 2.0.
It belongs to the org.apache.commons.math.analysis.solvers package.
Class Description:

The BisectionSolver class finds zeros of univariate real functions using the bisection algorithm.
The algorithm requires the function to be continuous.
Constructors:

Deprecated Constructor: Takes a UnivariateRealFunction and calls the superclass constructor with default values (maximum iterations and accuracy).
Default Constructor: Calls the superclass constructor with default values.
Solve Methods:

Deprecated solve Methods:
These methods solve the function within a given interval [min, max] and are marked as deprecated.
Active solve Methods:
These methods take a UnivariateRealFunction and solve it within the interval [min, max], optionally starting from an initial guess.
The main solve method implements the bisection algorithm:
It iteratively narrows down the interval [min, max] by checking the midpoint and adjusting the bounds based on the sign of the function's value at the midpoint.
It stops when the interval width is less than or equal to the absolute accuracy or the maximum number of iterations is reached.

Test Results:
The provided code is producing incorrect results. For examples:

• Running the function as follows solver.getAbsoluteAccuracy() generate a NullPointerException in line 4

    public void testMath369() throws Exception {
        UnivariateRealFunction f = new SinFunction();
        UnivariateRealSolver solver = new BisectionSolver();
        assertEquals(Math.PI, solver.solve(f, 3.0, 3.2, 3.1), solver.getAbsoluteAccuracy());
    }

Spectrum-based Fault Localization (SBFL) Techniques Results:
We have used SBFL techniques to identify potentially faulty lines. Here are the results of top-[X] suspicious lines sorted in descending order of the score:
Line 88 BisectionSolver, SBFL
Line 66 BisectionSolver, SBFL
Line 72 BisectionSolver, SBFL
...
Analyze the provided code and utilize task description, test results, and SBFL techniques results to help in identifying potentially faulty lines. Provide the results following this JSON template:

{
  "faultLoc": [    {      "faultyLine": (indicating the line number of the suspicious code),      "code": (displaying the actual code),      "explanation": (step by step reasoning on why this location is considered potentially faulty)    },    ...  ]
}

------------------------------------응답-------------------------

{
  "faultLoc": [
    {
      "faultyLine": 88,
      "code": "return solve(min, max);",
      "explanation": "The method solve(final UnivariateRealFunction f, double min, double max, double initial) should be solving using the provided function f but calls solve(min, max) without passing f. This could lead to incorrect function evaluation and is likely causing the issue."
    },
    {
      "faultyLine": 66,
      "code": "return solve(f, min, max);",
      "explanation": "The deprecated solve(double min, double max, double initial) method should call solve(final UnivariateRealFunction f, double min, double max, double initial) but instead calls solve(f, min, max). This misuse of the method might be contributing to the NullPointerException."
    },
    {
      "faultyLine": 72,
      "code": "return solve(f, min, max);",
      "explanation": "Similar to line 66, the deprecated solve(double min, double max) method should correctly call the intended solve method with the function parameter. Incorrectly calling solve(f, min, max) can lead to issues with uninitialized function evaluations."
    }
  ]
}

Explanation of Potential Fixes:
Line 88: Modify the call to ensure the function f is passed correctly to the solve method.

return solve(f, min, max);

Line 66: Ensure the call is consistent with the method signature that includes the initial guess.

return solve(f, min, max, initial);

Line 72: Similar to line 66, ensure proper method call with function parameter.

return solve(f, min, max);

By fixing these lines, the BisectionSolver should correctly handle the function parameter, preventing issues related to function evaluations and improving the accuracy of the bisection algorithm implementation.