
Thank you Peter.  That is very much helpful.  If you don't mind, I continued running the code to attempt to get my answer and I continue to get inf inf inf....... (printed around 100 times).
 
Any assistance with this issue.  Here is my code (including your corrections):
 

myquadrature<-function(f,a,b){
npts=length(f)
nint=npts-1
if(npts<=1)
error('need at least two points to integrate')
end;
if(b<=a)
error('something wrong with the interval, b should be greater than a')
else
dx=b/real(nint)
end;
npts=length(f)
int=0
int <- sum(f[-npts]+f[-1])/2*dx
}
 
#Call my quadrature
x=seq(0,2000,10)
h = 10.*(cos(((2*pi)/2000)*(x-mean(x)))+1)
u = 1.*(cos(((2*pi)/2000)*(x-mean(x)))+1)
a = x[1]
b = x[length(x)] 
plot(x,-h)
a = x[1];
b = x[length(x)];
#call your quadrature function.  Hint, the answer should be 30000.
f=u*h;
val =  myquadrature(f,a,b); ?  ___________This is where issue arises.  
result=myquadrature(val,0,2000)  ?
print(result)               ?  
 
 
Thanks again,
 
Phil
 
 
 		 	   		  
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