If statement not executing

I'm running into a really weird problem . In my Matlab code, the statement if (time == 0.0992) does not execute, but when I write it in the form if (time== 0.0016*62), it does execute.

Now, since 0.0016*62 is equal to 0.0992, I don't see why the first statement is any different from the second.

NOTE : 'time' is a variable who's value is used as a operating condition for the if statement

[Jan]

Welcome to the world of floating point numbers.

Answer 1

[Wayne King]

Hi, They aren't really equal:

a = 0.0016*62;
b = 0.0992;
isequal(a,b)

This is a well known problem discussed in this forum frequently with the representation of floating-point numbers.

You should use some tolerance statement like

      time = 0.0016*62;
      if(abs(time-0.0992)< eps)
      disp('True');
      else
      disp('False');
      end

Or something similar, trying to insist on equality with floating-point numbers is going to cause you a lot of problems.

Answer 2

[Image Analyst]

See the FAQ:

http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F