45 lines
1.0 KiB
C
45 lines
1.0 KiB
C
#include "square_root.h"
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/* See GNUmakefile in following link for explanation
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* https://exercism.io/my/solutions/103b2f7d92db42309c1988030f5202c7
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*/
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#if defined UNIT_TEST || defined DEBUG
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#include <stdio.h>
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#include <stdlib.h>
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#endif
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/* Newton's method:
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* https://en.wikipedia.org/wiki/Newton%27s_method#Square_root
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* return the largest integer equal or less than i square root.
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*/
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unsigned square_root(unsigned i)
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{
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unsigned sq, sq2;
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if (i<=1) /* 0 and 1 */
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return i;
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sq = i/2; /* we take i/2 as initial seed */
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sq2 = ((i/sq) + sq) / 2; /* first iteration */
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while (sq2 != sq) {
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sq = sq2;
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sq2 = ((i/sq) + sq) /2; /* next iteration */
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}
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return sq;
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}
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#ifdef UNIT_TEST
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int main(int ac, char **av)
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{
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int arg=1;
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unsigned i;
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for (; arg<ac; ++arg) {
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i=atol(av[arg]);
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printf("sqrt(%u)=%u\n", i, square_root(i));
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}
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}
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#endif
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