Doxygen Source Code Documentation
qmed.c File Reference
#include "mrilib.h"Go to the source code of this file.
Defines | |
| #define | MED3(a, b, c) |
| #define | SWAP(x, y) (temp=(x),(x)=(y),(y)=temp) |
Functions | |
| float | qmed_float (int n, float *ar) |
| int | main (int argc, char *argv[]) |
Define Documentation
|
|
Value: |
|
|
|
Function Documentation
|
||||||||||||
|
\** File : SUMA.c
Input paramters :
Definition at line 90 of file qmed.c. References argc, COX_cpu_time(), malloc, qmed_float(), and qsort_float().
00091 {
00092 int nn,ii , med , mrep=1 , jj ;
00093 float * ar , * br ;
00094 float mm ;
00095 double ct , ctsum=0.0 ;
00096
00097 if( argc < 2 ){printf("Usage: qmed N [m]\n");exit(0);}
00098 nn = strtol(argv[1],NULL,10) ; if( nn == 0 ) exit(1);
00099
00100 if( argc == 3 ){
00101 mrep = strtol(argv[2],NULL,10) ; if( mrep < 1 ) mrep = 1 ;
00102 }
00103
00104 med = ( nn > 0 ) ; if( !med ) nn = -nn ;
00105
00106 ar = (float *) malloc( sizeof(float)*nn ) ;
00107 br = (float *) malloc( sizeof(float)*nn ) ;
00108 srand48((long)(237+jj)) ;
00109 for( ii=0 ; ii < nn ; ii++ ) br[ii] = (float)(lrand48() % nn)*0.1 ;
00110
00111 ct = COX_cpu_time() ;
00112 for( jj=0 ; jj < mrep ; jj++ ){
00113
00114 memcpy( ar , br , sizeof(float)*nn ) ;
00115
00116 if( med ){
00117 mm = qmed_float( nn , ar ) ;
00118 } else {
00119 qsort_float( nn , ar ) ;
00120 if( nn%2 == 1 ) mm = ar[nn/2] ;
00121 else mm = 0.5*(ar[nn/2]+ar[nn/2-1]) ;
00122 }
00123 }
00124 ct = COX_cpu_time() - ct ;
00125 printf("Median = %g CPU = %g\n",mm,ct) ;
00126 exit(0) ;
00127 }
|
|
||||||||||||
|
Definition at line 21 of file qmed.c. References a, i, left, MED3, right, and SWAP. Referenced by extreme_proj(), find_unusual_correlations(), main(), median21_box_func(), median9_box_func(), mri_medianfilter(), qmedmad_float(), STATS_tsfunc(), THD_median_brick(), THD_outlier_count(), and unusuality().
00022 {
00023 register int i , j ; /* scanning indices */
00024 register float temp , pivot ; /* holding places */
00025 register float * a = ar ;
00026
00027 int left , right , mid , nodd ;
00028
00029 switch( n ){
00030 case 1: return ar[0] ;
00031 case 2: return 0.5*(ar[0]+ar[1]) ;
00032 case 3: return MED3( ar[0] , ar[1] , ar[2] ) ;
00033 }
00034
00035 left = 0 ; right = n-1 ; mid = n/2 ; nodd = ((n & 1) != 0) ;
00036
00037 /* loop while the subarray is at least 3 long */
00038
00039 while( right-left > 1 ){ /* work on subarray from left -> right */
00040
00041 i = ( left + right ) / 2 ; /* middle of subarray */
00042
00043 /* sort the left, middle, and right a[]'s */
00044
00045 if( a[left] > a[i] ) SWAP( a[left] , a[i] ) ;
00046 if( a[left] > a[right] ) SWAP( a[left] , a[right] ) ;
00047 if( a[i] > a[right] ) SWAP( a[right] , a[i] ) ;
00048
00049 pivot = a[i] ; /* a[i] is the median-of-3 pivot! */
00050 a[i] = a[right] ;
00051
00052 i = left ; /* initialize scanning */
00053 j = right ;
00054
00055 /*----- partition: move elements bigger than pivot up and elements
00056 smaller than pivot down, scanning in from ends -----*/
00057
00058 do{
00059 for( ; a[++i] < pivot ; ) ; /* scan i up, until a[i] >= pivot */
00060 for( ; a[--j] > pivot ; ) ; /* scan j down, until a[j] <= pivot */
00061
00062 if( j <= i ) break ; /* if j meets i, quit */
00063
00064 SWAP( a[i] , a[j] ) ;
00065 } while( 1 ) ;
00066
00067 /*----- at this point, the array is partitioned -----*/
00068
00069 a[right] = a[i] ; /* restore the pivot */
00070 a[i] = pivot ;
00071
00072 if( i == mid ){ /* good luck */
00073 if( nodd ) return pivot ; /* exact middle of array */
00074
00075 temp = a[left] ; /* must find next largest element below */
00076 for( j=left+1 ; j < i ; j++ )
00077 if( a[j] > temp ) temp = a[j] ;
00078
00079 return 0.5*(pivot+temp) ; /* return average */
00080 }
00081
00082 if( i < mid ) left = i ; /* throw away bottom partition */
00083 else right = i ; /* throw away top partition */
00084
00085 } /* end of while sub-array is long */
00086
00087 return (nodd) ? a[mid] : 0.5*(a[mid]+a[mid-1]) ;
00088 }
|
