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added round_to_E_series function to eseries lib.

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Jan Bader
2021-04-14 14:37:03 +02:00
parent feab9236d1
commit f56788f666
4 changed files with 56 additions and 2 deletions
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50
lib/eseries.c
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@@ -38,4 +38,54 @@ ESeriesMaxValue get_E_MAX(ESeries E_series) {
double round_to_E_series (double continuous_value, ESeries E_series) {
/*
* check for range. An E series is defined within one decade.
* values from 1 to 10 are accepted
*/
if (continuous_value >= 10 || continuous_value < 1) {
printf("eseries:round_to_E_series: Value out of range.\n");
return E_NIL;
}
double e_value = 0.0;
// set the max array index for given e series.
unsigned int e_max_values = get_E_MAX(E_series);
if (e_max_values == E_NIL) {
printf("eseries:round_to_E_series: Unknown E series.\n");
return E_NIL;
}
int upper_e_limit = e_max_values;
int lower_e_limit = 0;
for (int i = 0 ; i < log2((e_max_values/3)); i++) {
if (continuous_value < E_values[E_series][((upper_e_limit - lower_e_limit + 1) / 2) + lower_e_limit]) {
upper_e_limit = ((upper_e_limit - lower_e_limit + 1) / 2) + lower_e_limit - 1;
}
else {
lower_e_limit = ((upper_e_limit - lower_e_limit + 1) / 2) + lower_e_limit;
}
}
if (continuous_value < E_values[E_series][lower_e_limit + 1])
{
if (fabs(continuous_value - E_values[E_series][lower_e_limit]) < fabs(continuous_value - E_values[E_series][lower_e_limit + 1])) {
e_value = E_values[E_series][lower_e_limit];
}
else {
e_value = E_values[E_series][lower_e_limit + 1];
}
}
else {
if (fabs(continuous_value - E_values[E_series][upper_e_limit]) < fabs(continuous_value - E_values[E_series][upper_e_limit - 1])) {
e_value = E_values[E_series][upper_e_limit];
}
else {
e_value = E_values[E_series][upper_e_limit - 1];
}
}
return e_value;
}