agregated

Expression4J

Sample > Agregated expression

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Agregated expression
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Create an agregated expression

An agregated expression is constitued by :

function name (like f or foo or function)
parameters (like x or y or foo)
equal sign (=)
the body of the expression who use a previously defined expression

Expression does not support space. If spaces are present in the expression, the parsin will generate an error.

My first agregated expression with expression4j

try {
	Expression expression1 = 
	ExpressionFactory.createExpression("f(x,y)=2.4e-2*x-3.2*y");
	Expression expression2 = 
	ExpressionFactory.createExpression("g(x,y)=4*f(x,y)+3");

	System.out.println("Expression name: " + expression2.getName());
	System.out.println("Expression : " + expression2);
	System.out.println("Expression parameters: " + 
	expression2.getParameters());

	MathematicalElement me1 = NumberFactory.createReal(2);
	MathematicalElement me2 = NumberFactory.createReal(4);
	Parameters parameters = ExpressionFactory.createParameters();
	parameters.addParameter("x",me1);
	parameters.addParameter("y",me2);

	System.out.println("Value of expression g for x=2 and y = 4:" + 
	expression2.evaluate(parameters).getRealValue());

	me1 = NumberFactory.createReal(3);
	me2 = NumberFactory.createReal(2);
	parameters.addParameter("x",me1);
	parameters.addParameter("y",me2);
	System.out.println("Value of expression g for x=3 and y = 2:" + 
	expression2.evaluate(parameters).getRealValue());
}
catch (Exception e) {
	System.out.println("Error: " + e);
}


another sample:

public static void main(String[] args) {
	try {
		Expression expression1 = ExpressionFactory
			.createExpression("f(x,y)=2.4e-2*x-3.2*y");
		Expression expression2 = ExpressionFactory
			.createExpression("g(x,y)=4*f(x+3,f(y*2,x/2))+3");
		System.out.println("Expression name: " + expression2.getName());
		System.out.println("Expression : " + expression2);
		System.out.println("Expression parameters: " + 
			expression2.getParameters());

		MathematicalElement me1 = NumberFactory.createReal(2);
		MathematicalElement me2 = NumberFactory.createReal(4);
		Parameters parameters = ExpressionFactory.createParameters();
		parameters.addParameter("x",me1);
		parameters.addParameter("y",me2);
		System.out.println("Value of expression g for x=2 and y = 4:" + 
			expression2.evaluate(parameters).getRealValue());

		me1 = NumberFactory.createReal(3);
		me2 = NumberFactory.createReal(2);
		parameters.addParameter("x",me1);
		parameters.addParameter("y",me2);
		System.out.println("Value of expression g for x=3 and y = 2:" + 
			expression2.evaluate(parameters).getRealValue());
	}
	catch (Exception e) {
		System.out.println("Error: " + e);
	}
}