modulus

How do you deal with Java's weird behaviour with the modulus operator when using doubles? For example, you would expect the result of 3.9 - (3.9 % 0.1) to be 3.9 (and indeed, Google says I'm not going crazy), but when I run it in Java I get 3.8000000000000003 . I understand this is a result of how Java stores and processes doubles, but is there a way to work around it? Use a precise type if you need a precise result: double val = 3.9 - (3.9 % 0.1); System.out.println(val); // 3.8000000000000003 BigDecimal x = new BigDecimal( "3.9" ); BigDecimal bdVal = x.subtract( x.remainder( new BigDecimal(

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

I'm currently checking whether an entry in a loop is the 3rd iteration or not, with the following code: <?php for ($i = 0; $i < count($category_news); $i++) : ?> <div class="grid_8"> <div class="candidate snippet <?php if ($i % 3 == 2) echo "end"; ?>"> <div class="image shadow_50"> <img src="<?php echo base_url();?>media/uploads/news/<?php echo $category_news[$i]['url']; ?>" alt="Image Preview" width="70px" height="70px"/> </div> <h5><?php echo $category_news[$i]['title']?></h5> <p><?php echo strip_tags(word_limiter($category_news[$i]['article'], 15)); ?></p> <?php echo anchor('/news/article

Why does 49.90 % 0.10 in JavaScript return 0.09999999999999581 ? I expected it to be 0. Because JavaScript uses floating point math which always leads to rounding errors. If you need an exact result with two decimal places, multiply your numbers with 100 before the operation and then divide again afterwards: var result = ( 4990 % 10 ) / 100; Round if necessary. kennytm Javascript's Number is using "IEEE double-precision" to store the values. They are incapable of storing all decimal numbers exactly. The result is not zero because of round-off error when converting the decimal number to binary.

I am trying to implement the SAFER+ algorithm. The algorithm requires finding the modulus of a power function as follows: pow(45, x) mod 257 The variable x is a byte, and thus can range from 0 to 255. Accordingly, the result of the power function can be VERY big resulting in incorrect values if implemented using 32- or 64-bit integers. How can I perform this calculation? some pseudo code function powermod(base, exponent, modulus) { if (base < 1 || exponent < 0 || modulus < 1) return -1 result = 1; while (exponent > 0) { if ((exponent % 2) == 1) { result = (result * base) % modulus; } base =