From aca99a3386c8fc65a1a965cd04f9972b18491659 Mon Sep 17 00:00:00 2001 From: NunoSempere Date: Sun, 16 Jul 2023 12:26:55 +0200 Subject: [PATCH] added better error messages! --- scratchpad/scratchpad.c | 81 ++++++++++++++++++++++------------------- 1 file changed, 43 insertions(+), 38 deletions(-) diff --git a/scratchpad/scratchpad.c b/scratchpad/scratchpad.c index 5da623e..c6bf9e2 100644 --- a/scratchpad/scratchpad.c +++ b/scratchpad/scratchpad.c @@ -1,24 +1,19 @@ -#include // FLT_MAX, FLT_MIN #include // INT_MAX -#include #include -#include #include -#define VERBOSE 1 +#include // FLT_MAX, FLT_MIN +#include +#include // erf, sqrt + +#define EXIT_ON_ERROR 0 // Errors -// https://mccue.dev/pages/7-27-22-c-errors -// Huh, first time I've really needed a struct -// https://en.wikipedia.org/wiki/Struct_(C_programming_language) -// https://www.cs.yale.edu/homes/aspnes/pinewiki/C(2f)Structs.html -// https://stackoverflow.com/questions/9653072/return-a-struct-from-a-function-in-c -// options: -// - exit -// - pass structs -// to do: reuse more informative printing from build-your-own-lisp? +// [ ] to do: reuse more informative printing from build-your-own-lisp? +// Another option could be to exit on error. Maybe let the user decide? struct box { int empty; float content; + char * error_msg; }; // Example cdf @@ -48,23 +43,23 @@ float cdf_normal_0_1(float x) { float mean = 0; float std = 1; - return 0.5 * (1 + erf((x - mean) / (std * sqrt(2)))); + return 0.5 * (1 + erf((x - mean) / (std * sqrt(2)))); // erf from math.h } // Inverse cdf struct box inverse_cdf(float cdf(float), float p) { // given a cdf: [-Inf, Inf] => [0,1] - // returns x such that cdf(x) = p - // [x] to do: add bounds, add error checking - // [x] maybe return a struct or smth. + // 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) - // [x] to do: do smth with float min and float max? int interval_found = 0; while ((!interval_found) && (low > -FLT_MAX / 4) && (high < FLT_MAX / 4)) { // ^ Using FLT_MIN and FLT_MAX is overkill @@ -80,17 +75,18 @@ struct box inverse_cdf(float cdf(float), float p) high = high * 2; } } - if (0) { - printf("FLT_MIN = %f, FLT_MAX = %f, INT_MAX = %d\n", -FLT_MAX, FLT_MAX, INT_MAX); - printf("low: %f, high: %f\n", low, high); - printf("interval_found? %d\n", interval_found); - int while_condition = (!interval_found) && (low > FLT_MIN / 4) && (high < FLT_MAX / 4); - printf("while condition: %i\n", while_condition); - } - if (!interval_found) { - result.empty = 1; - return result; + 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; + } } else { int convergence_condition = 0; @@ -123,8 +119,18 @@ struct box inverse_cdf(float cdf(float), float p) result.content = low; result.empty = 0; } else { - result.empty = 1; - } + if(EXIT_ON_ERROR){ + printf("Search process did not converge, in function inverse_cdf, in %s (%d)", __FILE__, __LINE__); + exit(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; + } + result.empty = 1; + } return result; } @@ -146,13 +152,12 @@ uint32_t xorshift32(uint32_t* seed) } // Distribution & sampling functions - float rand_0_to_1(uint32_t* seed) { return ((float)xorshift32(seed)) / ((float)UINT32_MAX); } -// sampler based on inverse cdf +// Sampler based on inverse cdf struct box sampler(float cdf(float), uint32_t* seed) { struct box result; @@ -161,16 +166,15 @@ struct box sampler(float cdf(float), uint32_t* seed) return result; } -// ~~[-] to-do: integrals => beta distribution~~ -// => instead, use this incomplete beta function implementation, based on continuous fractions: +// to do: add beta. +// for the cdf, use this incomplete beta function implementation, based on continuous fractions: // // -// main with an example int main() { - // Uniform: + // Get the inverse cdf of a [0,1] uniform distribution at 0.5 struct box result_1 = inverse_cdf(cdf_uniform_0_1, 0.5); char* name_1 = "cdf_uniform_0_1"; if (result_1.empty) { @@ -180,7 +184,7 @@ int main() printf("Inverse of %s at %f is: %f\n", name_1, 0.5, result_1.content); } - // Squared cdf + // Get the inverse cdf of a [0,1] squared distribution at 0.5 struct box result_2 = inverse_cdf(cdf_squared_0_1, 0.5); char* name_2 = "cdf_squared_0_1"; if (result_2.empty) { @@ -190,7 +194,7 @@ int main() printf("Inverse of %s at %f is: %f\n", name_2, 0.5, result_2.content); } - // Normal cdf + // Get the inverse of a normal(0,1) cdf distribution struct box result_3 = inverse_cdf(cdf_normal_0_1, 0.5); char* name_3 = "cdf_normal_0_1"; if (result_3.empty) { @@ -200,6 +204,7 @@ int main() printf("Inverse of %s at %f is: %f\n", name_3, 0.5, result_3.content); } + // Use the sampler on a normal(0,1) // set randomness seed uint32_t* seed = malloc(sizeof(uint32_t)); *seed = 1000; // xorshift can't start with 0