?? sortind.c
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/* * Implement Heap sort -- direct and indirect sorting * Based on descriptions in Sedgewick "Algorithms in C" * Copyright (C) 1999 Thomas Walter * * 18 February 2000: Modified for GSL by Brian Gough * * This is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2, or (at your option) any * later version. * * This source is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * for more details. */#include <config.h>#include <stdlib.h>#include <gsl/gsl_heapsort.h>static inline void downheap (size_t * p, const void *data, const size_t size, const size_t N, size_t k, gsl_comparison_fn_t compare);#define CMP(data,size,j,k) (compare((const char *)(data) + (size) * (j), (const char *)(data) + (size) * (k)))static inline voiddownheap (size_t * p, const void *data, const size_t size, const size_t N, size_t k, gsl_comparison_fn_t compare){ const size_t pki = p[k]; while (k <= N / 2) { size_t j = 2 * k; if (j < N && CMP (data, size, p[j], p[j + 1]) < 0) { j++; } if (CMP (data, size, pki, p[j]) >= 0) { break; } p[k] = p[j]; k = j; } p[k] = pki;}intgsl_heapsort_index (size_t * p, const void *data, size_t count, size_t size, gsl_comparison_fn_t compare){ /* Sort the array in ascending order. This is a true inplace algorithm with N log N operations. Worst case (an already sorted array) is something like 20% slower */ size_t i, k, N; if (count == 0) { return GSL_SUCCESS; /* No data to sort */ } for (i = 0; i < count; i++) { p[i] = i ; /* set permutation to identity */ } /* We have n_data elements, last element is at 'n_data-1', first at '0' Set N to the last element number. */ N = count - 1; k = N / 2; k++; /* Compensate the first use of 'k--' */ do { k--; downheap (p, data, size, N, k, compare); } while (k > 0); while (N > 0) { /* first swap the elements */ size_t tmp = p[0]; p[0] = p[N]; p[N] = tmp; /* then process the heap */ N--; downheap (p, data, size, N, 0, compare); } return GSL_SUCCESS;}
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