Add examples/gamma_from_file.c

examples/gamma_from_file.c

@@ -0,0 +1,156 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <time.h>
+#include <flint/flint.h>
+#include <flint/acb.h>
+
+const slong bin_prec = 128; // binary precision for computation
+const long dec_prec = 38; // decimal digits
+
+void acb_set_str(acb_t z, const char *real_str, const char *imag_str) {
+
+    arb_t real_part, imag_part;
+    arb_init(real_part);
+    arb_init(imag_part);
+
+    // Set the real and imaginary parts from strings
+    if (arb_set_str(real_part, real_str, 128) == 1) {
+        fprintf(stderr, "Error setting real part from string: %s\n", real_str);
+        arb_clear(real_part);
+        arb_clear(imag_part);
+        return;
+    }
+
+    if (arb_set_str(imag_part, imag_str, 128) == 1) {
+        fprintf(stderr, "Error setting imaginary part from string: %s\n", imag_str);
+        arb_clear(real_part);
+        arb_clear(imag_part);
+        return;
+    }
+
+    // Combine into acb_t
+    acb_set_arb_arb(z, real_part, imag_part);
+    arb_clear(real_part);
+    arb_clear(imag_part);
+}
+
+void parse_complex_number_str(const char *input_line, char *real_part, char *imag_part) {
+    // Find the first space character
+    char *space_pos = strchr(input_line, ' ');
+    if (space_pos) {
+        // Get the real part
+        strncpy(real_part, input_line, space_pos - input_line);
+        real_part[space_pos - input_line] = '\0'; // Null-terminate
+
+        // Get the imaginary part
+        // Skip the space and copy the rest
+        strcpy(imag_part, space_pos + 1);
+
+        // Remove spaces from the imaginary part
+        char *src = imag_part, *dst = imag_part;
+        while (*src) {
+            if (*src != ' ') {
+                *dst++ = *src; // Copy non-space characters
+            }
+            src++;
+        }
+        *dst = '\0'; // Null terminate the modified imaginary part
+
+        // Remove all spaces and the '*I' from the imaginary part
+        char *imaginary_end = strstr(imag_part, "*I");
+        if (imaginary_end) {
+            *imaginary_end = '\0'; // Cut off the '*I'
+        }
+
+    } else {
+        fprintf(stderr, "Error: No space found in input line: '%s'\n", input_line);
+    }
+}
+
+void compute_gamma_from_file(const char *filename) {
+    FILE *file = fopen(filename, "r");
+    if (file == NULL) {
+        perror("Error opening file");
+        return;
+    }
+
+    char input_line[2 * dec_prec + 20];
+    char real_str[dec_prec + 10];
+    char imag_str[dec_prec + 10];
+
+    acb_t z, result;
+    acb_init(z);
+    acb_init(result);
+    unsigned long records = 0;
+
+    while (fgets(input_line, sizeof(input_line), file)) {
+
+        memset(real_str, 0, sizeof(real_str));
+        memset(imag_str, 0, sizeof(imag_str));
+
+        // Find and remove newline character
+        char *newline_pos = strchr(input_line, '\n');
+        if (newline_pos) {
+            *newline_pos = '\0'; // Replace newline with null terminator
+        }
+
+        // Print the raw input line for debugging
+/*
+        printf("Raw Input Line: '%s'\n", input_line);
+*/
+        if (strlen(input_line)) {
+            parse_complex_number_str(input_line, real_str, imag_str);
+        }
+
+        // Print parsed values for debugging
+/*
+        printf("Real:'%s'\n", real_str);
+        printf("Imag:'%s'\n", imag_str);
+*/
+        acb_set_str(z, real_str, imag_str);
+        acb_gamma(result, z, bin_prec);  // Compute Gamma(z)
+
+        // Print result
+        // Check for a minus sign in the imaginary part
+        printf("Gamma(%s%s*I) = ", real_str, imag_str);
+        acb_printd(result, 38); // Print with 38 decimal places
+        printf("\n");
+
+        records++; // Increment records for successfully processed line
+
+    }
+
+    printf("Read: %lu records\n", records);
+
+    acb_clear(z);
+    acb_clear(result);
+    fclose(file);
+}
+
+int main(int argc, char *argv[]) {
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
+        return EXIT_FAILURE;
+    }
+
+    clock_t start_time = clock(); // Start timing
+
+    compute_gamma_from_file(argv[1]);
+
+    clock_t end_time = clock(); // End timing
+    double time_taken = (double)(end_time - start_time) / CLOCKS_PER_SEC; // Convert to seconds
+    printf("Time taken: %.6f seconds\n", time_taken);
+
+    return EXIT_SUCCESS;
+}
+
+/* Input file format: <real part 38 digits> <sign of imag> <abs(imag part 38 digits)>*I
+------------------------------------------------------------------------------------
+-7.6863655401393771171569824218750000000 - 3.3994659781455993652343750000000000000*I
+-5.6718241423368453979492187500000000000 - 2.4417644459754228591918945312500000000*I
+etc.
+------------------------------------------------------------------------------------
+*/
+