division
Why is division more expensive than multiplication?
CPU’s ALU (Arithmetic-Logic Unit) executes algorithms, though they are implemented in hardware. Classic multiplications algorithms includes Wallace tree and Dadda tree. More information is available here. More sophisticated techniques are available in newer processors. Generally, processors strive to parallelize bit-pairs operations in order the minimize the clock cycles required. Multiplication algorithms can be parallelized quite … Read more
Division without using ‘/’
The typical way is to shift and subtract. This is basically pretty similar to long division as we learned it in school. The big difference is that in decimal division you need to estimate the next digit of the result. In binary, that’s trivial. The next digit is always either 0 or 1. If the … Read more
Negative integer division surprising result
For the actual values, i.e. 8.0/(-7.0), the result is roughly -1.143. Your result using integer division is being rounded down toward the more negative value of -2. (This is also known as “Floor division”) This is why you will get the somewhat perplexing answers of: >>> 8/(-7) -2 >>> 8/7 1 Note: This is “fixed” … Read more
Make division by zero equal to zero
Check if the denominator is zero before dividing. This avoids the overhead of catching the exception, which may be more efficient if you expect to be dividing by zero a lot. def weird_division(n, d): return n / d if d else 0
Is a list (potentially) divisible by another?
Build bipartite graph structure – connect a[i] with all its divisors from b[]. Then find maximum matching and check whether it is perfect matching (number of edges in matching is equal to the number of pairs (if graph is directed) or to doubled number). Arbitrary chosen Kuhn algorithm implementation here. Upd: @Eric Duminil made great … Read more
How to use division in JavaScript
Make one of those numbers a float. 737/parseFloat(1070) or a bit faster: 737*1.0/1070 convert to 2 decimal places Math.round(737 * 100.0 / 1070) / 100
VB.NET vs C# integer division [duplicate]
When you look at the IL-code that those two snippets produce, you’ll realize that VB.NET first converts the integer values to doubles, applies the division and then rounds the result before it’s converted back to int32 and stored in y. C# does none of that. VB.NET IL Code: IL_0000: ldc.i4.s 10 IL_0002: stloc.1 IL_0003: ldc.i4.s … Read more
Why doesn’t ‘d /= d’ throw a division by zero exception when d == 0?
C++ does not have a “Division by Zero” Exception to catch. The behavior you’re observing is the result of Compiler optimizations: The compiler assumes Undefined Behavior doesn’t happen Division by Zero in C++ is undefined behavior Therefore, code which can cause a Division by Zero is presumed to not do so. And, code which must … Read more
Integer division in Python 2 and Python 3
In Python 2.7, the / operator is integer division if inputs are integers. If you want float division (which is something I always prefer), just use this special import: from __future__ import division See it here: >>> 7 / 2 3 >>> from __future__ import division >>> 7 / 2 3.5 >>> Integer division is … Read more