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
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