How do I use modulus for float double

Question

I m creating an RPN calculator for a school project  I m having trouble with the modulus operator  Since we re using the double data type  modulus won t work on floating point numbers  For example  0 5   0 3 should return 0 2 but I m getting a division by zero exception   The instruction says to use fmod    I ve looked everywhere for fmod    including javadocs but I can t find it  I m starting to think it s a method I m going to have to create   edit  hmm  strange  I just plugged in those numbers again and it seems to be working fine   but just in case  Do I need to watch out using the mod operator in Java when using floating types  I know something like this can t be done in C    I think

User · Answer

I thought the regular modulus operator would work for this in java  but it can t be hard to code   Just divide the numerator by the denominator  and take the integer portion of the result   Multiply that by the denominator  and subtract the result from the numerator   x   n   d xint   Integer portion of x result   n - d   xint

User · Answer

fmod is the standard C function for handling floating-point modulus  I imagine your source was saying that Java handles floating-point modulus the same as C s fmod function  In Java you can use the   operator on doubles the same as on integers   int x   5   3     x   2 double y    5    3     y    2

User · Answer

Unlike C  Java allows using the   for both integer and floating point and  unlike C89 and C    it is well-defined for all inputs  including negatives    From JLS   15 17 3      The result of a floating-point   remainder operation is determined by   the rules of IEEE arithmetic          If either operand is NaN  the result is NaN    If the result is not NaN  the sign of the result equals the sign of   the dividend    If the dividend is an infinity  or the divisor is a zero  or both  the   result is NaN    If the dividend is finite and the divisor is an infinity  the result   equals the dividend    If the dividend is a zero and the divisor is finite  the result   equals the dividend    In the remaining cases  where neither an infinity  nor a zero  nor   NaN is involved  the floating-point   remainder r from the division of a   dividend n by a divisor d is defined   by the mathematical relation r n- d  q    where q is an integer that is negative   only if n d is negative and positive   only if n d is positive  and whose   magnitude is as large as possible   without exceeding the magnitude of the   true mathematical quotient of n and d       So for your example  0 5 0 3   1 6       q has the same sign  positive  as 0 5  the dividend   and the magnitude is 1  integer with largest magnitude not exceeding magnitude of 1 6      and r   0 5 -  0 3   1    0 2

User · Answer

You probably had a typo when you first ran it   evaluating 0 5   0 3 returns  0 2   A double  as expected   Mindprod has a good overview of how modulus works in Java

[java] How do I use modulus for float/double?

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