multiplication

Here is my short implementation of Russian Peasant Multiplication . How can it be improved? Restrictions : only works when a>0,b>0 for(p=0;p+=(a&1)*b,a!=1;a>>=1,b<<=1); Svante It can be improved by adding whitespace, proper indentation, and a proper function body: int peasant_mult (int a, int b) { for (p = 0; p += (a & 1) * b, a != 1; a /= 2, b *= 2); return p;} See? Now it's clear how the three parts of the for declaration are used. Remember, programs are written mainly for human eyes. Unreadable code is always bad code. And now, for my personal amusement, a tail recursive version: (defun

After some thought, I came up with the following code for multiplying two quaternions using SSE: #include <pmmintrin.h> /* SSE3 intrinsics */ /* multiplication of two quaternions (x, y, z, w) x (a, b, c, d) */ __m128 _mm_cross4_ps(__m128 xyzw, __m128 abcd) { /* The product of two quaternions is: */ /* (X,Y,Z,W) = (xd+yc-zb+wa, -xc+yd+za+wb, xb-ya+zd+wc, -xa-yb-zc+wd) */ __m128 wzyx = _mm_shuffle_ps(xyzw, xyzw, _MM_SHUFFLE(0,1,2,3)); __m128 baba = _mm_shuffle_ps(abcd, abcd, _MM_SHUFFLE(0,1,0,1)); __m128 dcdc = _mm_shuffle_ps(abcd, abcd, _MM_SHUFFLE(2,3,2,3)); /* variable names below are for

I have read this post on binary multiplication using two complement. but it is not very clear to me. Even I have difficulty understanding the wiki article on this. I want to know how to go about calculating multiplications of negative numbers: eg: -1 with -7 should give 7. A 4-bit, 2's complement of -1 is : 1111 A 4-bit, 2's complement of -7 is : 1001 some step-wise way of calculating the multiplication will be helpful. No article I came across talks about division. How to approach this? step 1: sign extend both integers to twice as many bits. This is safe to do, though may not always be

I hear this statement quite often, that multiplication on modern hardware is so optimized that it actually is at the same speed as addition. Is that true? I never can get any authoritative confirmation. My own research only adds questions. The speed tests usually show data that confuses me. Here is an example: #include <stdio.h> #include <sys/time.h> unsigned int time1000() { timeval val; gettimeofday(&val, 0); val.tv_sec &= 0xffff; return val.tv_sec * 1000 + val.tv_usec / 1000; } int main() { unsigned int sum = 1, T = time1000(); for (int i = 1; i < 100000000; i++) { sum += i + (i+1); sum++;

I can't belive what's happen in my program double den = 180*3600*10000 ; in debugging a got this value -2109934592.0000000 any help please ??? you can try this simple code #include<stdio.h> #include<math.h> int main ( int argc , char *argv ) { double denominator = 10000*180*3600 ; printf("%f \n", denominator ) ; return 0 ; } With the full code in the question we can now see it's an integer overflow. 10000 * 180 * 3600 = 6,480,000,000. This is greater than 2,147,483,648 which is the max value of a 32-bit signed int. The results of the multiplication overflows to -2,109,934,592 and is then

I want to multiply two 100-Digit Numbers In Excel using matrix. The issue in Excel is that after 15-digit, it shows only 0. So, the output also need to be in a Matrix. 1st Number: "9999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999" 2nd Number: "2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222" Output: