commit 84f94e2beae20780f8e4c76edd40d3fea3df7a6f
parent c487bdfaf5a3f43a56dd62d26033770914073407
Author: NunoSempere <nuno.sempere@protonmail.com>
Date: Sun, 16 Jul 2023 16:56:11 +0200
rework error as a macro
Diffstat:
2 files changed, 100 insertions(+), 44 deletions(-)
diff --git a/scratchpad/scratchpad b/scratchpad/scratchpad
Binary files differ.
diff --git a/scratchpad/scratchpad.c b/scratchpad/scratchpad.c
@@ -1,14 +1,26 @@
-#include <float.h> // FLT_MAX, FLT_MIN
-#include <limits.h> // INT_MAX
-#include <math.h> // erf, sqrt
+#include <float.h> // FLT_MAX, FLT_MIN
+#include <limits.h> // INT_MAX
+#include <math.h> // erf, sqrt
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define EXIT_ON_ERROR 0
+#define MAX_ERROR_LENGTH 500
+#define PROCESS_ERROR(...) \
+ do { \
+ if (EXIT_ON_ERROR) { \
+ printf("@, in %s (%d)", __FILE__, __LINE__); \
+ exit(1); \
+ } else { \
+ char error_msg[MAX_ERROR_LENGTH]; \
+ snprintf(error_msg, MAX_ERROR_LENGTH, "@, in %s (%d)", __FILE__, __LINE__); \
+ struct box error = { .empty = 1, .error_msg = error_msg }; \
+ return error; \
+ } \
+ } while (0)
-// Errors
struct box {
int empty;
float content;
@@ -76,16 +88,7 @@ struct box inverse_cdf(float cdf(float), float p)
}
if (!interval_found) {
- if (EXIT_ON_ERROR) {
- printf("Interval containing the target value not found, in function inverse_cdf, in %s (%d)", __FILE__, __LINE__);
- exit(1);
- } else {
- char error_msg[200];
- snprintf(error_msg, 200, "Interval containing the target value not found in function inverse_cdf, in %s (%d)", __FILE__, __LINE__);
- result.empty = 1;
- result.error_msg = error_msg;
- return result;
- }
+ PROCESS_ERROR("Interval containing the target value not found, in function inverse_cdf");
} else {
int convergence_condition = 0;
@@ -114,19 +117,90 @@ struct box inverse_cdf(float cdf(float), float p)
result.content = low;
result.empty = 0;
} else {
- if (EXIT_ON_ERROR) {
- printf("Search process did not converge, in function inverse_cdf, in %s (%d)", __FILE__, __LINE__);
- exit(1);
+ PROCESS_ERROR("Search process did not converge, in function inverse_cdf");
+ }
+
+ return result;
+ }
+}
+
+// Inverse cdf at point, but this time taking a struct box.
+struct box inverse_cdf_box(struct box cdf_box(float), float p)
+{
+ // given a cdf: [-Inf, Inf] => Box([0,1])
+ // returns a box with either
+ // x such that cdf(x) = p
+ // or an error
+ // if EXIT_ON_ERROR is set to 1, it exits instead of providing an error
+
+ struct box result;
+ float low = -1.0;
+ float high = 1.0;
+
+ // 1. Make sure that cdf(low) < p < cdf(high)
+ int interval_found = 0;
+ while ((!interval_found) && (low > -FLT_MAX / 4) && (high < FLT_MAX / 4)) {
+ // ^ Using FLT_MIN and FLT_MAX is overkill
+ // but it's also the *correct* thing to do.
+ struct box cdf_low = cdf_box(low);
+ if(cdf_low.empty){
+ PROCESS_ERROR(cdf_low.error_msg);
+ }
+
+ struct box cdf_high=cdf_box(high);
+ if(cdf_high.empty){
+ PROCESS_ERROR(cdf_low.error_msg);
+ }
+
+ int low_condition = (cdf_low.content < p);
+ int high_condition = (p < cdf_high.content);
+ if (low_condition && high_condition) {
+ interval_found = 1;
+ } else if (!low_condition) {
+ low = low * 2;
+ } else if (!high_condition) {
+ high = high * 2;
+ }
+ }
+
+ if (!interval_found) {
+ PROCESS_ERROR("Interval containing the target value not found, in function inverse_cdf");
+ } else {
+
+ int convergence_condition = 0;
+ int count = 0;
+ while (!convergence_condition && (count < (INT_MAX / 2))) {
+ float mid = (high + low) / 2;
+ int mid_not_new = (mid == low) || (mid == high);
+ // float width = high - low;
+ if (mid_not_new) {
+ // if ((width < 1e-8) || mid_not_new){
+ convergence_condition = 1;
} else {
- char error_msg[200];
- snprintf(error_msg, 200, "Search process did not converge, in function inverse_cdf, in %s (%d)", __FILE__, __LINE__);
- result.empty = 1;
- result.error_msg = error_msg;
- return result;
+ struct box cdf_mid = cdf_box(mid);
+ if(cdf_mid.empty){
+ PROCESS_ERROR(cdf_mid.error_msg);
+ }
+ float mid_sign = cdf_mid.content - p;
+ if (mid_sign < 0) {
+ low = mid;
+ } else if (mid_sign > 0) {
+ high = mid;
+ } else if (mid_sign == 0) {
+ low = mid;
+ high = mid;
+ }
}
}
- return result;
+ if (convergence_condition) {
+ result.content = low;
+ result.empty = 0;
+ return result;
+ } else {
+ PROCESS_ERROR("Search process did not converge, in function inverse_cdf");
+ }
+
}
}
@@ -211,16 +285,7 @@ struct box incbeta(float a, float b, float x)
struct box result;
if (x < 0.0 || x > 1.0) {
- if (EXIT_ON_ERROR) {
- printf("x = %f, x out of bounds [0, 1], in function incbeta, in %s (%d)", __FILE__, __LINE__);
- exit(1);
- } else {
- char error_msg[200];
- snprintf(error_msg, 200, "x = %f, x out of bounds [0, 1], in function incbeta, in %s (%d)", x, __FILE__, __LINE__);
- result.empty = 1;
- result.error_msg = error_msg;
- return result;
- }
+ PROCESS_ERROR("x out of bounds [0, 1], in function incbeta");
}
/*The continued fraction converges nicely for x < (a+1)/(a+b+2)*/
@@ -276,16 +341,7 @@ struct box incbeta(float a, float b, float x)
}
}
- if (EXIT_ON_ERROR) {
- printf("More loops needed, did not converge, in function incbeta, in %s (%d)", __FILE__, __LINE__);
- exit(1);
- } else {
- char error_msg[200];
- snprintf(error_msg, 200, "More loops needed, did not converge, in function incbeta, in %s (%d)", __FILE__, __LINE__);
- result.empty = 1;
- result.error_msg = error_msg;
- return result;
- }
+ PROCESS_ERROR("More loops needed, did not converge, in function incbeta");
}
struct box cdf_beta(float x)
@@ -412,6 +468,6 @@ int main()
}
clock_t end_3 = clock();
float time_spent_3 = (float)(end_3 - begin_3) / CLOCKS_PER_SEC;
- printf("Time spent: %f", time_spent_3);
+ printf("Time spent: %f\n", time_spent_3);
return 0;
}
