diff --git a/squiggle.c/makefile b/squiggle.c/makefile index bce0055c..99f7d54d 100644 --- a/squiggle.c/makefile +++ b/squiggle.c/makefile @@ -1,7 +1,7 @@ OUTPUT=./samples build: - gcc -O3 samples.c ./squiggle_c/squiggle.c ./squiggle_c/squiggle_more.c -lm -fopenmp -o $(OUTPUT) + gcc -O3 -march=native samples.c ./squiggle_c/squiggle.c ./squiggle_c/squiggle_more.c -lm -fopenmp -o $(OUTPUT) install: rm -r squiggle_c diff --git a/squiggle.c/samples b/squiggle.c/samples deleted file mode 100755 index ebc32148..00000000 Binary files a/squiggle.c/samples and /dev/null differ diff --git a/squiggle.c/samples.c b/squiggle.c/samples.c index 33e21674..bfd09f20 100644 --- a/squiggle.c/samples.c +++ b/squiggle.c/samples.c @@ -3,7 +3,7 @@ #include #include -int main() +double sampler_result(uint64_t * seed) { double p_a = 0.8; double p_b = 0.5; @@ -17,10 +17,11 @@ int main() int n_dists = 4; double weights[] = { 1 - p_c, p_c / 2, p_c / 4, p_c / 4 }; double (*samplers[])(uint64_t*) = { sample_0, sample_1, sample_few, sample_many }; - double sampler_result(uint64_t * seed) - { - return sample_mixture(samplers, weights, n_dists, seed); - } + return sample_mixture(samplers, weights, n_dists, seed); +} + +int main() +{ int n_samples = 1000 * 1000, n_threads = 16; double* results = malloc((size_t)n_samples * sizeof(double)); diff --git a/squiggle.c/squiggle_c/squiggle_more.c b/squiggle.c/squiggle_c/squiggle_more.c index d3a4f636..4441ce26 100644 --- a/squiggle.c/squiggle_c/squiggle_more.c +++ b/squiggle.c/squiggle_c/squiggle_more.c @@ -43,15 +43,14 @@ void sampler_parallel(double (*sampler)(uint64_t* seed), double* results, int n_ int divisor_multiple = quotient * n_threads; // uint64_t** seeds = malloc((size_t)n_threads * sizeof(uint64_t*)); - seed_cache_box* cache_box = (seed_cache_box*) malloc(sizeof(seed_cache_box) * (size_t)n_threads); - // seed_cache_box cache_box[n_threads]; + seed_cache_box* cache_box = (seed_cache_box*)malloc(sizeof(seed_cache_box) * (size_t)n_threads); + // seed_cache_box cache_box[n_threads]; // we could use the C stack. On normal linux machines, it's 8MB ($ ulimit -s). However, it doesn't quite feel right. srand(1); for (int i = 0; i < n_threads; i++) { // Constraints: // - xorshift can't start with 0 // - the seeds should be reasonably separated and not correlated cache_box[i].seed = (uint64_t)rand() * (UINT64_MAX / RAND_MAX); - // printf("#%ld: %lu\n",i, *seeds[i]); // Other initializations tried: // *seeds[i] = 1 + i; @@ -60,22 +59,51 @@ void sampler_parallel(double (*sampler)(uint64_t* seed), double* results, int n_ } int i; -#pragma omp parallel private(i, quotient) +#pragma omp parallel private(i) { #pragma omp for for (i = 0; i < n_threads; i++) { - int quotient = n_samples / n_threads; + // It's possible I don't need the for, and could instead call omp + // in some different way and get the thread number with omp_get_thread_num() int lower_bound_inclusive = i * quotient; int upper_bound_not_inclusive = ((i + 1) * quotient); // note the < in the for loop below, + for (int j = lower_bound_inclusive; j < upper_bound_not_inclusive; j++) { results[j] = sampler(&(cache_box[i].seed)); - // Could also result in inefficient cache stuff, but hopefully not too often + /* + t starts at 0 and ends at T + at t=0, + thread i accesses: results[i*quotient +0], + thread i+1 acccesses: results[(i+1)*quotient +0] + at t=T + thread i accesses: results[(i+1)*quotient -1] + thread i+1 acccesses: results[(i+2)*quotient -1] + The results[j] that are directly adjacent are + results[(i+1)*quotient -1] (accessed by thread i at time T) + results[(i+1)*quotient +0] (accessed by thread i+1 at time 0) + and these are themselves adjacent to + results[(i+1)*quotient -2] (accessed by thread i at time T-1) + results[(i+1)*quotient +1] (accessed by thread i+1 at time 2) + If T is large enough, which it is, two threads won't access the same + cache line at the same time. + Pictorially: + at t=0 ....i.........I......... + at t=T .............i.........I + and the two never overlap + Note that results[j] is a double, a double has 8 bytes (64 bits) + 8 doubles fill a cache line of 64 bytes. + So we specifically won't get problems as long as n_samples/n_threads > 8 + n_threads is normally 16, so n_samples > 128 + Note also that this is only a problem in terms of speed, if n_samples<128 + the results are still computed, it'll just be slower + */ } } } for (int j = divisor_multiple; j < n_samples; j++) { results[j] = sampler(&(cache_box[0].seed)); - // we can just reuse a seed, this isn't problematic because we are not doing multithreading + // we can just reuse a seed, + // this isn't problematic because we;ve now stopped doing multithreading } free(cache_box); @@ -88,7 +116,7 @@ typedef struct ci_t { double high; } ci; -static void swp(int i, int j, double xs[]) +inline static void swp(int i, int j, double xs[]) { double tmp = xs[i]; xs[i] = xs[j]; @@ -120,7 +148,7 @@ static double quickselect(int k, double xs[], int n) { // https://en.wikipedia.org/wiki/Quickselect - double *ys = malloc((size_t)n * sizeof(double)); + double* ys = malloc((size_t)n * sizeof(double)); memcpy(ys, xs, (size_t)n * sizeof(double)); // ^: don't rearrange item order in the original array @@ -161,18 +189,222 @@ ci array_get_90_ci(double xs[], int n) return array_get_ci((ci) { .low = 0.05, .high = 0.95 }, xs, n); } -ci sampler_get_ci(ci interval, double (*sampler)(uint64_t*), int n, uint64_t* seed) +double array_get_median(double xs[], int n) { - UNUSED(seed); // don't want to use it right now, but want to preserve ability to do so (e.g., remove parallelism from internals). Also nicer for consistency. - double* xs = malloc((size_t)n * sizeof(double)); - sampler_parallel(sampler, xs, 16, n); - ci result = array_get_ci(interval, xs, n); - free(xs); - return result; + int median_k = (int)floor(0.5 * n); + return quickselect(median_k, xs, n); } -ci sampler_get_90_ci(double (*sampler)(uint64_t*), int n, uint64_t* seed) + +/* array print: potentially useful for debugging */ +void array_print(double xs[], int n) { - return sampler_get_ci((ci) { .low = 0.05, .high = 0.95 }, sampler, n, seed); + printf("["); + for (int i = 0; i < n - 1; i++) { + printf("%f, ", xs[i]); + } + printf("%f", xs[n - 1]); + printf("]\n"); +} + +void array_print_stats(double xs[], int n) +{ + ci ci_90 = array_get_ci((ci) { .low = 0.05, .high = 0.95 }, xs, n); + ci ci_80 = array_get_ci((ci) { .low = 0.1, .high = 0.9 }, xs, n); + ci ci_50 = array_get_ci((ci) { .low = 0.25, .high = 0.75 }, xs, n); + double median = array_get_median(xs, n); + double mean = array_mean(xs, n); + double std = array_std(xs, n); + printf("| Statistic | Value |\n" + "| --- | --- |\n" + "| Mean | %lf |\n" + "| Median | %lf |\n" + "| Std | %lf |\n" + "| 90%% confidence interval | %lf to %lf |\n" + "| 80%% confidence interval | %lf to %lf |\n" + "| 50%% confidence interval | %lf to %lf |\n", + mean, median, std, ci_90.low, ci_90.high, ci_80.low, ci_80.high, ci_50.low, ci_50.high); +} + +void array_print_histogram(double* xs, int n_samples, int n_bins) +{ + // Interface inspired by + if (n_bins <= 1) { + fprintf(stderr, "Number of bins must be greater than 1.\n"); + return; + } else if (n_samples <= 1) { + fprintf(stderr, "Number of samples must be higher than 1.\n"); + return; + } + + int* bins = (int*)calloc((size_t)n_bins, sizeof(int)); + if (bins == NULL) { + fprintf(stderr, "Memory allocation for bins failed.\n"); + return; + } + + // Find the minimum and maximum values from the samples + double min_value = xs[0], max_value = xs[0]; + for (int i = 0; i < n_samples; i++) { + if (xs[i] < min_value) { + min_value = xs[i]; + } + if (xs[i] > max_value) { + max_value = xs[i]; + } + } + + // Avoid division by zero for a single unique value + if (min_value == max_value) { + max_value++; + } + + // Calculate bin width + double bin_width = (max_value - min_value) / n_bins; + + // Fill the bins with sample counts + for (int i = 0; i < n_samples; i++) { + int bin_index = (int)((xs[i] - min_value) / bin_width); + if (bin_index == n_bins) { + bin_index--; // Last bin includes max_value + } + bins[bin_index]++; + } + + // Calculate the scaling factor based on the maximum bin count + int max_bin_count = 0; + for (int i = 0; i < n_bins; i++) { + if (bins[i] > max_bin_count) { + max_bin_count = bins[i]; + } + } + const int MAX_WIDTH = 50; // Adjust this to your terminal width + double scale = max_bin_count > MAX_WIDTH ? (double)MAX_WIDTH / max_bin_count : 1.0; + + // Print the histogram + for (int i = 0; i < n_bins; i++) { + double bin_start = min_value + i * bin_width; + double bin_end = bin_start + bin_width; + + int decimalPlaces = 1; + if ((0 < bin_width) && (bin_width < 1)) { + int magnitude = (int)floor(log10(bin_width)); + decimalPlaces = -magnitude; + decimalPlaces = decimalPlaces > 10 ? 10 : decimalPlaces; + } + printf("[%*.*f, %*.*f", 4 + decimalPlaces, decimalPlaces, bin_start, 4 + decimalPlaces, decimalPlaces, bin_end); + char interval_delimiter = ')'; + if (i == (n_bins - 1)) { + interval_delimiter = ']'; // last bucket is inclusive + } + printf("%c: ", interval_delimiter); + + int marks = (int)(bins[i] * scale); + for (int j = 0; j < marks; j++) { + printf("█"); + } + printf(" %d\n", bins[i]); + } + + // Free the allocated memory for bins + free(bins); +} + +void array_print_90_ci_histogram(double* xs, int n_samples, int n_bins) +{ + // Code duplicated from previous function + // I'll consider simplifying it at some future point + // Possible ideas: + // - having only one function that takes any confidence interval? + // - having a utility function that is called by both functions? + ci ci_90 = array_get_90_ci(xs, n_samples); + + if (n_bins <= 1) { + fprintf(stderr, "Number of bins must be greater than 1.\n"); + return; + } else if (n_samples <= 10) { + fprintf(stderr, "Number of samples must be higher than 10.\n"); + return; + } + + int* bins = (int*)calloc((size_t)n_bins, sizeof(int)); + if (bins == NULL) { + fprintf(stderr, "Memory allocation for bins failed.\n"); + return; + } + + double min_value = ci_90.low, max_value = ci_90.high; + + // Avoid division by zero for a single unique value + if (min_value == max_value) { + max_value++; + } + double bin_width = (max_value - min_value) / n_bins; + + // Fill the bins with sample counts + int below_min = 0, above_max = 0; + for (int i = 0; i < n_samples; i++) { + if (xs[i] < min_value) { + below_min++; + } else if (xs[i] > max_value) { + above_max++; + } else { + int bin_index = (int)((xs[i] - min_value) / bin_width); + if (bin_index == n_bins) { + bin_index--; // Last bin includes max_value + } + bins[bin_index]++; + } + } + + // Calculate the scaling factor based on the maximum bin count + int max_bin_count = 0; + for (int i = 0; i < n_bins; i++) { + if (bins[i] > max_bin_count) { + max_bin_count = bins[i]; + } + } + const int MAX_WIDTH = 40; // Adjust this to your terminal width + double scale = max_bin_count > MAX_WIDTH ? (double)MAX_WIDTH / max_bin_count : 1.0; + + // Print the histogram + int decimalPlaces = 1; + if ((0 < bin_width) && (bin_width < 1)) { + int magnitude = (int)floor(log10(bin_width)); + decimalPlaces = -magnitude; + decimalPlaces = decimalPlaces > 10 ? 10 : decimalPlaces; + } + printf("(%*s, %*.*f): ", 6 + decimalPlaces, "-∞", 4 + decimalPlaces, decimalPlaces, min_value); + int marks_below_min = (int)(below_min * scale); + for (int j = 0; j < marks_below_min; j++) { + printf("█"); + } + printf(" %d\n", below_min); + for (int i = 0; i < n_bins; i++) { + double bin_start = min_value + i * bin_width; + double bin_end = bin_start + bin_width; + + printf("[%*.*f, %*.*f", 4 + decimalPlaces, decimalPlaces, bin_start, 4 + decimalPlaces, decimalPlaces, bin_end); + char interval_delimiter = ')'; + if (i == (n_bins - 1)) { + interval_delimiter = ']'; // last bucket is inclusive + } + printf("%c: ", interval_delimiter); + + int marks = (int)(bins[i] * scale); + for (int j = 0; j < marks; j++) { + printf("█"); + } + printf(" %d\n", bins[i]); + } + printf("(%*.*f, %*s): ", 4 + decimalPlaces, decimalPlaces, max_value, 6 + decimalPlaces, "+∞"); + int marks_above_max = (int)(above_max * scale); + for (int j = 0; j < marks_above_max; j++) { + printf("█"); + } + printf(" %d\n", above_max); + + // Free the allocated memory for bins + free(bins); } /* Algebra manipulations */ @@ -225,216 +457,3 @@ ci convert_lognormal_params_to_ci(lognormal_params y) ci result = { .low = exp(loglow), .high = exp(loghigh) }; return result; } - -/* Scaffolding to handle errors */ -// We will sample from an arbitrary cdf -// and that operation might fail -// so we build some scaffolding here - -#define MAX_ERROR_LENGTH 500 -#define EXIT_ON_ERROR 0 -#define PROCESS_ERROR(error_msg) process_error(error_msg, EXIT_ON_ERROR, __FILE__, __LINE__) - -typedef struct box_t { - int empty; - double content; - char* error_msg; -} box; - -box process_error(const char* error_msg, int should_exit, char* file, int line) -{ - if (should_exit) { - printf("%s, @, in %s (%d)", error_msg, file, line); - exit(1); - } else { - char error_msg[MAX_ERROR_LENGTH]; - snprintf(error_msg, MAX_ERROR_LENGTH, "@, in %s (%d)", file, line); // NOLINT: We are being carefull here by considering MAX_ERROR_LENGTH explicitly. - box error = { .empty = 1, .error_msg = error_msg }; - return error; - } -} - -/* Invert an arbitrary cdf at a point */ -// Version #1: -// - input: (cdf: double => double, p) -// - output: Box(number|error) -box inverse_cdf_double(double cdf(double), double p) -{ - // given a cdf: [-Inf, Inf] => [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 - - double low = -1.0; - double high = 1.0; - - // 1. Make sure that cdf(low) < p < cdf(high) - int interval_found = 0; - while ((!interval_found) && (low > -DBL_MAX / 4) && (high < DBL_MAX / 4)) { - // for floats, use FLT_MAX instead - // Note that this approach is overkill - // but it's also the *correct* thing to do. - - int low_condition = (cdf(low) < p); - int high_condition = (p < cdf(high)); - 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) { - return 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))) { - double mid = (high + low) / 2; - int mid_not_new = (mid == low) || (mid == high); - // double width = high - low; - // if ((width < 1e-8) || mid_not_new){ - if (mid_not_new) { - convergence_condition = 1; - } else { - double mid_sign = cdf(mid) - p; - if (mid_sign < 0) { - low = mid; - } else if (mid_sign > 0) { - high = mid; - } else if (mid_sign == 0) { - low = mid; - high = mid; - } - } - } - - if (convergence_condition) { - box result = { .empty = 0, .content = low }; - return result; - } else { - return PROCESS_ERROR("Search process did not converge, in function inverse_cdf"); - } - } -} - -// Version #2: -// - input: (cdf: double => Box(number|error), p) -// - output: Box(number|error) -box inverse_cdf_box(box cdf_box(double), double 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 - - double low = -1.0; - double high = 1.0; - - // 1. Make sure that cdf(low) < p < cdf(high) - int interval_found = 0; - while ((!interval_found) && (low > -DBL_MAX / 4) && (high < DBL_MAX / 4)) { - // for floats, use FLT_MAX instead - // Note that this approach is overkill - // but it's also the *correct* thing to do. - box cdf_low = cdf_box(low); - if (cdf_low.empty) { - return PROCESS_ERROR(cdf_low.error_msg); - } - - box cdf_high = cdf_box(high); - if (cdf_high.empty) { - return 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) { - return 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))) { - double mid = (high + low) / 2; - int mid_not_new = (mid == low) || (mid == high); - // double width = high - low; - if (mid_not_new) { - // if ((width < 1e-8) || mid_not_new){ - convergence_condition = 1; - } else { - box cdf_mid = cdf_box(mid); - if (cdf_mid.empty) { - return PROCESS_ERROR(cdf_mid.error_msg); - } - double 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; - } - } - } - - if (convergence_condition) { - box result = { .empty = 0, .content = low }; - return result; - } else { - return PROCESS_ERROR("Search process did not converge, in function inverse_cdf"); - } - } -} - -/* Sample from an arbitrary cdf */ -// Before: invert an arbitrary cdf at a point -// Now: from an arbitrary cdf, get a sample -box sampler_cdf_box(box cdf(double), uint64_t* seed) -{ - double p = sample_unit_uniform(seed); - box result = inverse_cdf_box(cdf, p); - return result; -} -box sampler_cdf_double(double cdf(double), uint64_t* seed) -{ - double p = sample_unit_uniform(seed); - box result = inverse_cdf_double(cdf, p); - return result; -} -double sampler_cdf_danger(box cdf(double), uint64_t* seed) -{ - double p = sample_unit_uniform(seed); - box result = inverse_cdf_box(cdf, p); - if (result.empty) { - exit(1); - } else { - return result.content; - } -} - -/* array print: potentially useful for debugging */ -void array_print(double xs[], int n) -{ - printf("["); - for (int i = 0; i < n - 1; i++) { - printf("%f, ", xs[i]); - } - printf("%f", xs[n - 1]); - printf("]\n"); -} diff --git a/squiggle.c/squiggle_c/squiggle_more.h b/squiggle.c/squiggle_c/squiggle_more.h index 2f88349a..6ff601b6 100644 --- a/squiggle.c/squiggle_c/squiggle_more.h +++ b/squiggle.c/squiggle_c/squiggle_more.h @@ -4,15 +4,18 @@ /* Parallel sampling */ void sampler_parallel(double (*sampler)(uint64_t* seed), double* results, int n_threads, int n_samples); -/* Get 90% confidence interval */ +/* Stats */ +double array_get_median(double xs[], int n); typedef struct ci_t { double low; double high; } ci; ci array_get_ci(ci interval, double* xs, int n); ci array_get_90_ci(double xs[], int n); -ci sampler_get_ci(ci interval, double (*sampler)(uint64_t*), int n, uint64_t* seed); -ci sampler_get_90_ci(double (*sampler)(uint64_t*), int n, uint64_t* seed); + +void array_print_stats(double xs[], int n); +void array_print_histogram(double* xs, int n_samples, int n_bins); +void array_print_90_ci_histogram(double* xs, int n, int n_bins); /* Algebra manipulations */ @@ -31,24 +34,9 @@ lognormal_params algebra_product_lognormals(lognormal_params a, lognormal_params lognormal_params convert_ci_to_lognormal_params(ci x); ci convert_lognormal_params_to_ci(lognormal_params y); -/* Error handling */ -typedef struct box_t { - int empty; - double content; - char* error_msg; -} box; -#define MAX_ERROR_LENGTH 500 -#define EXIT_ON_ERROR 0 -#define PROCESS_ERROR(error_msg) process_error(error_msg, EXIT_ON_ERROR, __FILE__, __LINE__) -box process_error(const char* error_msg, int should_exit, char* file, int line); -void array_print(double* array, int length); +/* Utilities */ -/* Inverse cdf */ -box inverse_cdf_double(double cdf(double), double p); -box inverse_cdf_box(box cdf_box(double), double p); - -/* Samplers from cdf */ -box sampler_cdf_double(double cdf(double), uint64_t* seed); -box sampler_cdf_box(box cdf(double), uint64_t* seed); +#define THOUSAND 1000 +#define MILLION 1000000 #endif