exponentiation

问题 I found a fast binary logarithm algorithm for fixed points in an answer to this question: Fast fixed point pow, log, exp and sqrt, based on an algorithm by Clay S. Turner. Is it possible to "reverse" this to calculate fractional powers of two? e.g: // log2(3) = 1.5849609375 log2fix(196608, 16) == 103872 pow2fix(103872, 16) == 196608 Here's the code from Dan Moulding: #include <errno.h> #include <stddef.h> #include "log2fix.h" int32_t log2fix (uint32_t x, size_t precision) { int32_t b = 1U <<

问题 I need to perform modular exponentiation on quite large numbers on both python3 and javascript. I have functions that do the task, but they give me different outputs. Python (all of the three work in the same way): pow(176672119508, 55, 200000023499) def expmod_iter(a,b,c): x = 1 while(b>0): if(b&1==1): x = (x*a)%c a=(a*a)%c b >>= 1 return x%c def pow_mod(x, y, z): number = 1 while y: if y & 1: number = number * x % z y >>= 1 x = x * x % z return number # The result is always 124912252967 and

问题 def f(a, b, c): return ((a ** b)-1) // c % b Can this script be faster in some way? (I have been looking for something with modular exponentiation): pow(a, b, c) == a ** b % c but this above script doesn't seem to be improvable like that. Does anyone know a way to speedup the above script? Thanks in advance. Edit: The second script is not at all the same as the first one, it is just meant to show what kind of optimization I had in mind. Edit: I didn't put the exact equation in becouse I

问题 I am trying to compute a^b^c mod p for some positive integers a,b,c,p. One possible (and obvious) way is to use fast modular exponentiation which will run in O(log(b^c))=clog(b) . While I don't mind the efficiency here, the obvious downfall of this method is that you need an explicit binary representation of b^c which in itself is already exponential. So the question for me is, if I can not represent b^c as a binary representation, is there a way I can compute a^b^c mod p from the binary

问题 How do i determine the first n digits of an exponentiation (a b ). eg: for a = 12, b = 13 & n = 4, the first 4 digits are 1069. 回答1: Calculate a b by the following iterations: a 1 = a 1 , a 2 = a 2 , ... a i = a i , ... a b = a b You have a i+1 = a i ×a . Calcluate each a i not exactly. The thing is that the relative error of a b is less than n times relative error of a . You want to get final relative error less than 10 -n . Thus relative error on each step may be . Remove last digits at

问题 How do i determine the first n digits of an exponentiation (a b ). eg: for a = 12, b = 13 & n = 4, the first 4 digits are 1069. 回答1: Calculate a b by the following iterations: a 1 = a 1 , a 2 = a 2 , ... a i = a i , ... a b = a b You have a i+1 = a i ×a . Calcluate each a i not exactly. The thing is that the relative error of a b is less than n times relative error of a . You want to get final relative error less than 10 -n . Thus relative error on each step may be . Remove last digits at

问题 i am working on an apps for calculating fuel... i need to know how i can power a number in 10? the Excel code is "10^1.5" 回答1: If you mean in XCode, you have to #include <math.h> and then you can use pow : double res=pow(10, 1.5); 来源： https://stackoverflow.com/questions/5810108/in-10-power-calculation-power-calculations

问题 I've come across an interesting exercise and it says: Implement a function x^y using standard functions of Turbo Pascal For integer variables I can use for loop but I cannot understand how to work with real variables in this case. I've been thinking about how to do this using Taylor series (can't understand how to use it for exponentiation) and I also found out that x^y = exp(y*log(x)) but there is only ln (natural logarithm) in standard functions... PS I'm not asking you to write code: give

问题 as a starter in ASM programming i am need to get the result of 2 to the power of 38 in Assembly , and i need your help in understanding why is my program doesn't produce the result i am need (it prints 4 decimal): .386 .model flat, stdcall option casemap:none include \masm32\include\windows.inc include \masm32\include\msvcrt.inc includelib \masm32\lib\msvcrt.lib .data formatstr db "%d",0 .code start: mov eax , 2 mov ecx , 38 mov esi , eax mov edx , 0 .while TRUE mul esi mov esi, edx add esi,

问题 I have do to a question to write a method to input an array of type LONG that stores the values of all the powers of 2 from 0 to 63 (i.e. 2 0 to 2 63 ) Output the contects of the array screen. Hint: Math.pow(x,y) is ued to put number x to exponent y so far I have something like I keep getting error or Math.pow(size,2); required long, found double. I tried Math.pow(i,2); I get same error./ possible loss of precision ,, any help :) thanks class ws3q2 { public static void main(String[]args) {