Problem with abs(double)

This is a discussion on Problem with abs(double) within the C++ Programming forums, part of the General Programming Boards category; It's very basic but I have problem getting the absolute value of a double type; here: Code: double *Dist_cb1= new ...

  1. #1
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    Problem with abs(double)

    It's very basic but I have problem getting the absolute value of a double type; here:

    Code:
    double *Dist_cb1= new double[2400];
    for (i=0; i<2400; i++){
    		Dist_cb1[i]=0;
    		for (j=0; j<6; j++)
    			
    			Dist_cb1[i] = Dist_cb1[i] + abs(abs(Dataf[j] - train1[i][j])); printf("%f        ", Dist_cb1[i]);
    			
    	}
    when I try to get the absolute value of the subtraction of two doubles I receive a large value which should be an address.

  2. #2
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    You want to be using 'fabs' here.
    iMalc: Your compiler doesn't accept misspellings and bad syntax, so why should we?
    justin777: I have no idea what you are talking about sorry, I use a laptop and there is no ascii eject or something

  3. #3
    and the Hat of Guessing tabstop's Avatar
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    I don't know if you're doing it deliberately, but putting that printf statement on the same line as the assignment to Dist_cb1[i] would lead people to think that it will happen every time through the loop, when it won't.

    There's no point in doing abs() twice I wouldn't think either. Note that abs is overloaded to work with floats and doubles and things if you use std::abs instead of just abs.

  4. #4
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    Quote Originally Posted by tabstop View Post
    There's no point in doing abs() twice I wouldn't think either. Note that abs is overloaded to work with floats and doubles and things if you use std::abs instead of just abs.
    ..... and you #include <cmath> (at least, for the float/double overloading).
    Right 98% of the time, and don't care about the other 3%.

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