C# (If < or If >) vs Math.Sign

Question

Might be a silly question, but is there any reason to use Math.Sign?

Is there a speed/optimization thing with using Math.Sign rather than just using an if statement? Perhaps just a best practice/code readability preference?

if (rayDirX < 0) 
    stepX = -1; 
else 
    stepX = 1;

//----------

stepX = (rayDirX < 0) ? (-1) : (1);

//----------

stepX = Math.Sign(rayDirX);

Answer 1

I doubt there is a functional difference or much, if any, perf difference but the Math.Sign version is a little more visibly straight forward. Especially in your example where the Type of rayDirX is not declared. But it's pretty subtle and I wouldn't criticize you for using either.

EDIT:

And one other thing, your example above has a slight bug. In the case of 0 Math.Sign will return 0. Here is the decompiled code out of the framework for Math.Sign:

public static int Sign(int value)
{
  if (value < 0)
  {
    return -1;
  }
  if (value > 0)
  {
    return 1;
  }
  return 0;
}

Answer 2

Math.Sign can be used as part of a larger expression. You could also get the sign for use in an expression via the ternary operator, but not everything thinks the ternary operator is all that readable.