java校验数学公式_java基于mesp计算和实现数学公式、数学表达式

import com.graphbuilder.math.Expression;

import com.graphbuilder.math.ExpressionTree;

import com.graphbuilder.math.FuncMap;

import com.graphbuilder.math.VarMap;

//java基于mesp计算和实现数学公式、数学表达式

//http://sourceforge.net/projects/expression-tree/files/

public class mesp {

public static void main(String[] args) {

//test001();

test002();

}

private static void test002() {

//y=ax2+bx+c

Expression expression=ExpressionTree.parse("a*x^2+b*x+c");

VarMap vm = new VarMap(false);

vm.setValue("a", 1);

vm.setValue("b", 2);

vm.setValue("c", 1);

vm.setValue("x", 1);

//y=x^2+2x+1=(x+1)^2

double result=expression.eval(vm, null);

System.out.println(result);

vm.setValue("a", 1);

vm.setValue("b", 4);

vm.setValue("c", 4);

vm.setValue("x", 1);

//y=x^2+4x+4=(x+2)^2

result=expression.eval(vm, null);

System.out.println(result);

}

private static void test001() {

String s = "pi*r^2";

Expression x = ExpressionTree.parse(s);

VarMap vm = new VarMap(false /* case sensitive */);

vm.setValue("pi", Math.PI);

vm.setValue("r", 5);

FuncMap fm = null; // no functions in expression

System.out.println(x); // (pi*(r^2))

System.out.println(x.eval(vm, fm)); // 78.53981633974483

vm.setValue("r", 10);

System.out.println(x.eval(vm, fm)); // 314.1592653589793

}

}