public static IntegrationFunction parse(String string) throws InvalidIntegralException {
variablesNames = new ArrayList<String>();
countVariables(string);
try {
if (variablesNames.size() == 0) {
return new ConstantFunction(Double.parseDouble(string));
}
ExpressionBuilder builder = new ExpressionBuilder(string);
builder.withVariableNames("x", "y", "z");
final Calculable calc = builder.build();
IntegrationFunction function =
new IntegrationFunction() {
@Override
public double evaluate(double... args) {
if (args.length == 1) {
return calc.calculate(args[0], 0, 0);
} else if (args.length == 2) {
return calc.calculate(args[0], args[1], 0);
} else {
return calc.calculate(args);
}
}
};
return function;
} catch (UnknownFunctionException e) {
throw new InvalidIntegralException(e);
} catch (UnparsableExpressionException e) {
throw new InvalidIntegralException(e);
}
}
/*
* Sets the actual expression string for this expression
*/
private void setExpressions(String start, String end) {
startBuilder = new ExpressionBuilder(start);
endBuilder = new ExpressionBuilder(end);
for (String n : getAllSymbols()) {
startBuilder.withVariable(new Variable(n));
endBuilder.withVariable(new Variable(n));
}
}
