/**
* Evaluates and returns the value of the expression as a double number.
*
* @return The calculated value of the expression as a double number. If the type of the value
* does not implement the Number interface (e.g. Complex), NaN is returned. If an error occurs
* during evaluation, NaN is returned and hasError() will return true.
* @see #getComplexValue()
*/
public double getValue() {
Object value = getValueAsObject();
if (value == null) return Double.NaN;
if (value instanceof Complex) {
Complex c = (Complex) value;
if (c.im() != 0.0) return Double.NaN;
return c.re();
}
if (value != null && value instanceof Number) {
return ((Number) value).doubleValue();
}
return Double.NaN;
}
