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);

I'm so glad that I'm not the only one who thinks this method is pretty much pointless... — Mike G, Dec 04 '12 at 16:07
A method name is more descriptive than an algebraic expression, and encapsulates the constants to prevent repetition and the possibility for error. — Dan Puzey, Dec 06 '12 at 10:42

justin.m.chase · Accepted Answer · 2012-03-12T18:51:38.283

5

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;
}

edited Mar 12 '12 at 18:51

answered Mar 12 '12 at 18:46

justin.m.chase

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Ten years later latest C# version also compares against 0.0, which makes it a little bit uglier and slower – Trap Aug 21 '22 at 01:40

score 4 · Answer 2 · answered Mar 12 '12 at 18:44

4

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.

answered Mar 12 '12 at 18:44

Joel Coehoorn

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Dan Puzey · Answer 3 · 2012-12-06T10:43:18.180

4

There is a functional difference: Math.Sign has three possible return values, and will return zero if the input is 0. You can't do that with a (single) ternary operator.

(Source)

Also, a method name is more descriptive than an algebraic expression, and encapsulates the constants to prevent repetition and the possibility for error.

edited Dec 06 '12 at 10:43

answered Mar 12 '12 at 18:52

Dan Puzey

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You can do it with two ternary expressions in one though `rayDirX < 0 ? -1 : rayDirX > 0 ? 1 : 0;` – justin.m.chase Mar 24 '12 at 16:21

score 0 · Answer 4 · answered Mar 12 '12 at 18:52

0

I think its mostly a readability issue. I didn't see anything in the reference that points to any differences. But as Joel said, Math.sign(rayDirX) is much easier to use as a part of a larger expression that the if block or conditional expression.

answered Mar 12 '12 at 18:52

Corwin01

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

4 Answers4