97 lines
2.1 KiB
C
97 lines
2.1 KiB
C
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/* peach (7400, altivec supported, 450MHz, gcc -O)
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m1 = 1.20000000000000018, exp = 1.19999999999999996
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m2 = 1.19999999999998885, exp = 1.19999999999999996
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*/
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/* peach (7400, altivec supported, 450MHz, gcc)
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m1 = 1.20000000000000018, exp = 1.19999999999999996
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m2 = 1.19999999999998885, exp = 1.19999999999999996
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*/
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/* phoenix, gcc -O
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m1 = 1.19999999999999996, exp = 1.19999999999999996
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m2 = 1.19999999999999996, exp = 1.19999999999999996
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*/
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/* phoenix, icc -O
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m1 = 1.19999999999999996, exp = 1.19999999999999996
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m2 = 1.19999999999999996, exp = 1.19999999999999996
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*/
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/* phoenix, gcc -O, iropt-level=2
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m1 = 1.20000000000000040, exp = 1.19999999999999996
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m2 = 1.19999999999999440, exp = 1.19999999999999996
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*/
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/* phoenix, gcc -O, iropt-level=1/0
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m1 = 1.20000000000000018, exp = 1.19999999999999996
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m2 = 1.19999999999998885, exp = 1.19999999999999996
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <math.h>
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#define NNN 1000
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double
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my_mean1 (const double data[], size_t stride, const size_t size)
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{
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/* Compute the arithmetic mean of a dataset using the recurrence relation
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mean_(n) = mean(n-1) + (data[n] - mean(n-1))/(n+1) */
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long double mean = 0;
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size_t i;
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for (i = 0; i < size; i++)
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{
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mean += (data[i * stride] - mean) / (i + 1);
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}
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return mean;
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}
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double
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my_mean2 (const double data[], size_t stride, const size_t size)
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{
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/* Compute the arithmetic mean of a dataset using the
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obvious scheme. */
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int i;
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long double sum = 0;
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for (i = 0; i < size; i++)
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sum += data[i * stride];
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return sum / (double)size;
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}
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int main (void)
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{
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int i;
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const size_t nacc2 = NNN+1;
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double numacc2[NNN+1] ;
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numacc2[0] = 1.2 ;
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for (i = 1 ; i < NNN; i += 2)
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numacc2[i] = 1.1 ;
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for (i = 1 ; i < NNN; i += 2)
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numacc2[i+1] = 1.3 ;
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#if 1
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asm __volatile__("fninit");
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#endif
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{
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double m1 = my_mean1 (numacc2, 1, nacc2);
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double m2 = my_mean2 (numacc2, 1, nacc2);
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double expected_mean = 1.2;
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printf("m1 = %19.17f, exp = %19.17f\n", m1, expected_mean);
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printf("m2 = %19.17f, exp = %19.17f\n", m2, expected_mean);
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}
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return 0;
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}
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