rpuzonas/harvensine-compute
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implement horners rule

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This commit is contained in:
Rokas Puzonas 2025-06-16 23:04:33 +03:00
parent 8c72530390
commit c59b28926f
1 changed files with 37 additions and 7 deletions
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44
src/math_func_checker.c
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@ -154,6 +154,23 @@ static f64 sin_using_taylor(f64 input, f64 *coeffs, size_t coeffs_len)
return result; return result;
} }
static f64 sin_using_taylor_horner(f64 input, f64 *coeffs, size_t coeffs_len)
{
f64 input_sqr = input * input;
f64 result = coeffs[coeffs_len - 1];
for (size_t j = 1; j < coeffs_len; j++) {
size_t i = coeffs_len - j - 1;
result *= input_sqr;
result += coeffs[i];
}
result *= input;
return result;
}
static void tester_record_result(struct tester *tester, f64 input, f64 my_output, f64 reference_output) static void tester_record_result(struct tester *tester, f64 input, f64 my_output, f64 reference_output)
{ {
f64 error = reference_output - my_output; f64 error = reference_output - my_output;
@ -182,19 +199,32 @@ static void test_taylor_series(u64 samples, f64 *coeffs, size_t coeffs_len)
create_taylor_series_coeffs(coeffs, coeffs_len); create_taylor_series_coeffs(coeffs, coeffs_len);
struct tester tester = { }; struct tester tester = { };
struct tester tester_horner = { };
for (int j = 0; j < samples; j++) { for (int j = 0; j < samples; j++) {
f64 input = lerp((f64)j / samples, -M_PI, M_PI); f64 input = lerp((f64)j / samples, 0, M_PI/2);
tester_record_result(&tester, input, sin_using_taylor(input, coeffs, coeffs_len), sin(input)); tester_record_result(&tester, input, sin_using_taylor(input, coeffs, coeffs_len), sin(input));
tester_record_result(&tester_horner, input, sin_using_taylor_horner(input, coeffs, coeffs_len), sin(input));
} }
char name[64] = { 0 }; {
snprintf(name, sizeof(name), "taylor %zu", coeffs_len); char name[64] = { 0 };
tester_show_result(&tester, name); snprintf(name, sizeof(name), "taylor %zu", coeffs_len);
tester_show_result(&tester, name);
}
{
char name[64] = { 0 };
snprintf(name, sizeof(name), "taylor h %zu", coeffs_len);
tester_show_result(&tester_horner, name);
}
printf(" diff %.16f\n", tester.max_error - tester_horner.max_error);
} }
int main() int main()
{ {
uint64_t samples = 10000; uint64_t samples = 100000;
struct math_spec specs[] = { struct math_spec specs[] = {
{ {
.name = "sin", .name = "sin",
@ -267,8 +297,8 @@ int main()
tester_show_result(&tester, spec.name); tester_show_result(&tester, spec.name);
} }
f64 taylor_coeffs[41]; f64 taylor_coeffs[10];
for (int i = 3; i < ARRAY_LEN(taylor_coeffs); i++) { for (int i = 1; i < ARRAY_LEN(taylor_coeffs); i++) {
test_taylor_series(samples, taylor_coeffs, i); test_taylor_series(samples, taylor_coeffs, i);
} }