[R] How to get correct integration in C for step function?
Lynette
fuyaonv at hotmail.com
Mon Jan 22 00:24:13 CET 2007
Dear all,
I am using Rdqags in C to realize the integration. It seems for the
continous C function I can get correct results. However, for step functions,
the results are not correct. For example, the following one, when integrated
from 0 to 1 gives 1 instead of the correct 1.5
void func( double *x, int n, void *ex )
{
int i;
for(i=0;i<n;i++) { x[i]=( ((x>=1/4)&&(x<=3/4)) ? 2:1 ) ; }
return;
}
while the following one when integrated from 0 to 1 gives the correct
0.7853983
void func( double *x, int n, void *ex )
{
int i;
for(i=0;i<n;i++) { x[i]= pow(1-x[i]*x[i],.5); }
return;
}
Please advise the problems. Thanks a lot.
Best,
Lynette
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