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| Newsgroups | comp.arch.arithmetic |
| Date | Sat, 11 Oct 2014 06:05:59 -0700 (PDT) |
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| Subject | Re: New appromixation for integer division by 63 or 127 |
| From | nikolaos.kavvadias@gmail.com |
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I have updated my claims for the algorithm. It works for all tested constant divisors (n=2 to n=16), and given the following assumption:
the range for x is [0,2^(2*n)-2], i.e. for n = 6, the range indeed is
0:4094.
And a test program:
[code]
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
/* main:
*/
int main(void)
{
int qapprox, qexact;
int i, j, k;
for (i = 2; i < 8; i++) {
for (j = 1; j < (1<<i)*(1<<i)-1; j++) {
k = (1<<i) - 1;
qapprox = (((j>>i)+j+((1<<i)+1))>>i)-1;
qexact = j / k;
if (qapprox != qexact) {
fprintf(stderr, "qapprox = (%d/%d) = %d\tqexact = (%d/%d) = %d\n",
j, k, qapprox, j, k, qexact);
}
}
}
return 0;
}
[/code]
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New appromixation for integer division by 63 or 127 nikolaos.kavvadias@gmail.com - 2014-10-11 00:19 -0700
Re: New appromixation for integer division by 63 or 127 nikolaos.kavvadias@gmail.com - 2014-10-11 06:05 -0700
Re: New appromixation for integer division by 63 or 127 Terje Mathisen <terje.mathisen@tmsw.no> - 2014-10-13 10:20 +0200
Re: New appromixation for integer division by 63 or 127 nikolaos.kavvadias@gmail.com - 2014-10-15 01:09 -0700
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