modulo

How do computers find modulus?

非 Y 不嫁゛ 提交于 2019-11-30 19:40:24
Is there some cool algorithm with bit wise operations? Often, the modulus and divide operations on a processor are the same thing. For instance, refer to http://jsimlo.sk/docs/cpu/index.php/div.html . This is the implementation of the divide instruction on Intel processors. Most of the time, modulus is just computed by dividing the two numbers. The quotient is stored in one register, and the remainder is stored in the other register. You would go after the remainder. If the divisor is known in advance (e.g. for code produced by a C compiler, this is a constant known at compile time) then

Modulus division when first number is smaller than second number

喜欢而已 提交于 2019-11-30 18:14:40
I apologize if this is a simple question but I'm having trouble grasping the concept of modulus division when the first number is smaller than the second number. For example when 1 % 4 my book says the remainder is 1. I don't understand how 1 is the remainder of 1 % 4. 1 / 4 is 0.25. Am I thinking about modulus division incorrectly? First, in Java, % is the remainder (not modulo) operator, which has slightly different semantics. That said, you need to think in terms of integer-only division, as if there were no fractional values. Think of it as storing items that cannot be divided: you can

Efficient Modulo 3 operation? [duplicate]

五迷三道 提交于 2019-11-30 18:11:19
问题 This question already has answers here : Closed 8 years ago . Possible Duplicate: Fast modulo 3 or division algorithm? Everyone knows that modulo arithmetic can be a huge drawback on performance. Does anyone know of a good alternative for x%3 operations? I know that one exists for x%2, but I really need one for modulo 3 since I want to alternate between three buffers in a for loop. Thanks! 回答1: Well instead of the usual "measure it" stuff an actual answer - because that stuff is actually real

Lua replacement for the % operator

时光怂恿深爱的人放手 提交于 2019-11-30 16:53:49
I want to check, if a number is divisible by another number: for i = 1, 100 do if i % 2 == 0 then print( i .. " is divisible.") end end This should work without any problems, but with the Lua in my server the script doesn't run if there is a % in the script... I dont know whats the reason, so is there any "replacement" for that? So I could check the number divsibility? Thank you. It's not ideal, but according to the Lua 5.2 Reference Manual : a % b == a - math.floor(a/b)*b lhf Use math.fmod(x,y) which does what you want: Returns the remainder of the division of x by y that rounds the quotient

Lua replacement for the % operator

风流意气都作罢 提交于 2019-11-30 14:29:38
问题 I want to check, if a number is divisible by another number: for i = 1, 100 do if i % 2 == 0 then print( i .. " is divisible.") end end This should work without any problems, but with the Lua in my server the script doesn't run if there is a % in the script... I dont know whats the reason, so is there any "replacement" for that? So I could check the number divsibility? Thank you. 回答1: It's not ideal, but according to the Lua 5.2 Reference Manual: a % b == a - math.floor(a/b)*b 回答2: Use math

How can I Initialize a div_t Object?

白昼怎懂夜的黑 提交于 2019-11-30 09:21:12
问题 So the order of the members returned from the div functions seems to be implementation defined. Is quot the 1 st member or is rem ? Let's say that I'm doing something like this: generate(begin(digits), end(digits), [i = div_t{ quot, 0 }]() mutable { i = div(i.quot, 10); return i.rem; }) Of course the problem here is that I don't know if I initialized i.quot or i.rem in my lambda capture. Is intializing i with div(quot, 1) the only cross platform way to do this? 回答1: EDIT: I think the VS

'MOD' is not a recognized built-in function name

China☆狼群 提交于 2019-11-30 07:59:15
I wanted to use MOD function in SQL Server 2008R2 and followed this link but still got the message: 'MOD' is not a recognized built-in function name. DECLARE @m INT SET @m = MOD(321,11) SELECT @m Error: Msg 195, Level 15, State 10, Line 2 'MOD' is not a recognized built-in function name. Why I can't use this function from the link above? The MOD keyword only exists in the DAX language (tabular dimensional queries), not TSQL Use % instead. Ref: Modulo In TSQL, the modulo is done with a percent sign. SELECT 38 % 5 would give you the modulo 3 for your exact sample, it should be like this. DECLARE

Why is modulus operator slow?

半城伤御伤魂 提交于 2019-11-30 07:12:58
Paraphrasing from in "Programming Pearls" book (about c language on older machines, since book is from the late 90's): Integer arithmetic operations ( + , - , * ) can take around 10 nano seconds whereas the % operator takes up to 100 nano seconds. Why there is that much difference? How does a modulus operator work internally? Is it same as division ( / ) in terms of time? The modulus/modulo operation is usually understood as the integer equivalent of the remainder operation - a side effect or counterpart to division. Except for some degenerate cases (where the divisor is a power of the

How do you do modulo or remainder in Erlang?

本秂侑毒 提交于 2019-11-30 05:35:59
I'm brand new to Erlang. How do you do modulo (get the remainder of a division)? It's % in most C-like languages, but that designates a comment in Erlang. Several people answered with rem, which in most cases is fine. But I'm revisiting this because now I need to use negative numbers and rem gives you the remainder of a division, which is not the same as modulo for negative numbers. grifaton In Erlang, 5 rem 3. gives 2 , and -5 rem 3. gives -2 . If I understand your question, you would want -5 rem 3. to give 1 instead, since -5 = -2 * 3 + 1. Does this do what you want? mod(X,Y) when X > 0 -> X

Efficient (cycles wise) algorithm to compute modulo 25?

浪子不回头ぞ 提交于 2019-11-30 04:09:39
I have a code in which i am computing x % 25. x always takes a positive value but its dynamic range is large. I found out that this particular code piece of computing a x % 25 is taking large cycles. I need to optimize it. Pre-computed lookup table is ruled out due to the possible large memory size of the table. As second approach i coded a fragment below(C code) - mod(a, b) { int r = a; while(r >= b) { r = r - b; } return r; } 1.) How can i optimize this code further for cycles(squeeze it to max)? 2.) Is there any entirely different optimized way to achieve x % 25( i know its not a common