Solve() exception

[alfredorosa80]

Hi, my java code is:

public static void evaluateLinearSystem() { try {

        F.initSymbols(null);
        EvalUtilities util = new EvalUtilities();
        StringBufferWriter buf = new StringBufferWriter();
       String input = "Solve[{1.0*d*q4+1.0*e == 100,1.0*c*q3 == 100,1.0*a*q1 == 100,1.0*e*q5 == 100,1.0*b*q2 == 100}, {a,b,c,d,e}]";

        IExpr result = util.evaluate(input);
        OutputFormFactory.get().convert(buf, result);
        String output = buf.toString();
        System.out.println("Evaluation for " + input + " is " + output);



    } catch (Exception e) {
        e.printStackTrace();
    }
}

It returns the following exception:

java.lang.NullPointerException at org.matheclipse.core.eval.EvalEngine.evalObject(EvalEngine.java:873) at org.matheclipse.core.eval.EvalEngine.evalLoop(EvalEngine.java:824) at org.matheclipse.core.eval.EvalEngine.evalWithoutNumericReset(EvalEngine.java:278) at org.matheclipse.core.eval.EvalEngine.evaluate(EvalEngine.java:297) at org.matheclipse.core.eval.EvalEngine.eval(EvalEngine.java:337) at org.matheclipse.core.expression.F.eval(F.java:2859) at org.matheclipse.core.reflection.system.Roots.rootsOfVariable(Roots.java:123) at org.matheclipse.core.reflection.system.Solve.rootsOfUnivariatePolynomial(Solve.java:421) at org.matheclipse.core.reflection.system.Solve.analyzeSublist(Solve.java:330) at org.matheclipse.core.reflection.system.Solve.analyzeSublist(Solve.java:359) at org.matheclipse.core.reflection.system.Solve.analyzeSublist(Solve.java:359) at org.matheclipse.core.reflection.system.Solve.analyzeSublist(Solve.java:359) at org.matheclipse.core.reflection.system.Solve.analyzeSublist(Solve.java:359) at org.matheclipse.core.reflection.system.Solve.evaluate(Solve.java:499) at org.matheclipse.core.eval.EvalEngine.evalASTBuiltinFunction(EvalEngine.java:644) at org.matheclipse.core.eval.EvalEngine.evalAST(EvalEngine.java:560) at org.matheclipse.core.eval.EvalEngine.evalObject(EvalEngine.java:874) at org.matheclipse.core.eval.EvalEngine.evalLoop(EvalEngine.java:837) at org.matheclipse.core.eval.EvalEngine.evalWithoutNumericReset(EvalEngine.java:278) at org.matheclipse.core.eval.EvalEngine.evaluate(EvalEngine.java:297) at org.matheclipse.core.eval.EvalUtilities.evaluate(EvalUtilities.java:45)

Where am I wrong?

Thanks in advance, Best Regards, Alfredo Rosa

[Axel Kramer]

Try this with the latest downloads!?

package org.matheclipse.core.examples;

import org.matheclipse.core.eval.EvalUtilities;
import org.matheclipse.core.form.output.OutputFormFactory;
import org.matheclipse.core.interfaces.IExpr;

public class SolveExample {
    public static void main(String[] args) {
        try {
            EvalUtilities util = new EvalUtilities();
            String input = "Solve [{d*q4+e == 100,c*q3 == 100,a*q1 == 100,e*q5 == 100,b*q2 == 100}, {a,b,c,d,e}]";
            IExpr result = util.evaluate(input);

            StringBuffer buf = new StringBuffer();
            OutputFormFactory.get().convert(buf, result);
            String output = buf.toString();
            System.out.println("Evaluation for " + input + " is " + output);

            input = "Solve[{1.0*d*q4+1.0*e == 100,1.0*c*q3 == 100,1.0*a*q1 == 100,1.0*e*q5 == 100,1.0*b*q2 == 100}, {a,b,c,d,e}]";
            result = util.evaluate(input);
            buf = new StringBuffer();
            OutputFormFactory.get().convert(buf, result);
            output = buf.toString();
            System.out.println("Evaluation for " + input + " is " + output);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}