cs_cumsum.c
Go to the documentation of this file.00001 #include "cs.h" 00002 /* p [0..n] = cumulative sum of c [0..n-1], and then copy p [0..n-1] into c */ 00003 double cs_cumsum (int *p, int *c, int n) 00004 { 00005 int i, nz = 0 ; 00006 double nz2 = 0 ; 00007 if (!p || !c) return (-1) ; /* check inputs */ 00008 for (i = 0 ; i < n ; i++) 00009 { 00010 p [i] = nz ; 00011 nz += c [i] ; 00012 nz2 += c [i] ; /* also in double to avoid int overflow */ 00013 c [i] = p [i] ; /* also copy p[0..n-1] back into c[0..n-1]*/ 00014 } 00015 p [n] = nz ; 00016 return (nz2) ; /* return sum (c [0..n-1]) */ 00017 }