sin(pi()) does not return 0 in DDMathParser

Question

I'm making a calculator app using DDMathParser. The problem I'm facing is sin(pi()) doesn't return 0 but a trivial number like 1.2246...e-16. I'm just wondering is there any way to convert it to 0? Thank you.

Answer 1

The -description method on NSNumber does not accurately represent the underlying number:

NSLog(@"%f", sin(M_PI));    // logs 0.000000
NSLog(@"%@", @(sin(M_PI))); // logs 1.224646799147353e-16

To work around this, you can pull out the -doubleValue of the NSNumber, and that should give you 0:

NSLog(@"%f", @(sin(M_PI)).doubleValue); // logs 0.000000