loop function and integrate?
On 30-11-2012, at 19:34, Berend Hasselman wrote:
On 30-11-2012, at 16:08, faeriewhisper wrote:
Hi guys!
I have to compute something and i don't know what i'm doing wrong. my code
is a bit complex, but imagine that is something like this:
a = c(1,2,3,4)
ia = length(a)
x = seq(1,100,length=0.1)
ib = length(x)
int1 = numeric(ib)
b = numeric(ib)
for(j in 1:ia) {
H = function(x) {sin(x + a[j])}
for(i in 1:ib) {
int = integrate(H, lower = 0, upper = x[i])
int1[i] = int[1]
b[i] = 1 + a[i]
}
end
int1 = unlist(int1)
int2 = int1*b
ss[j] = sum(int2)
}
end
What are you doing?
What's the "end" doing in your code in two places.
end is a function to extract and encode the last observation of a time series object. See ?end
It makes absolutely no sense to put them in your code.
Remove them immediately.
You haven't declared ss to be a vector.
So before the start of the j loop insert ss <- numeric(ia)
And simplify your code:
ss <- numeric(ia)
for(j in 1:ia) {
H = function(x) {sin(x + a[j])}
for(i in 1:ib) {
int = integrate(H, lower = 0, upper = x[i])
int1[i] = int$value
b[i] = 1 + a[i]
}
ss[j] = sum(int1*b)
}
ss
And more simplification is possible by eliminating b, which I leave to you.
There is no need to define the function H in the j loop.
You could do this:
H = function(x,A) {sin(x + A)}
for(j in 1:ia) {
aj <- a[j]
for(i in 1:ib) {
int = integrate(H, lower = 0, upper = x[i], A=aj)
int1[i] = (1 + a[i])* int$value
}
ss[j] = sum(int1)
}
And if Rui is right a[i] can be replaced by aj.
Berend