Thank you both. Maybe I was somewhat unclear still, but it should be
for i in 2:n, j in 1:n
C[j,i-1] = A[i,1] * B[j,i]
end
At least to do what I was trying to explain above.
On Monday, September 14, 2015 at 9:21:45 PM UTC-4, Ismael VC wrote:
>
> Could also be with this syntax:
>
>
> for i in 2:i, j in 1:j
> C[i,j] = A[i,1] * B[j,i]
> end
>
>
>
> El lunes, 14 de septiembre de 2015, 20:08:12 (UTC-5), Tom Breloff escribió:
>>
>> How about you do it in a loop (note this should be done in a function...
>> globals will ruin performance):
>>
>> C = Array(n,n-1)
>> for i in 2:i
>> for j in 1:j
>> C[i,j] = A[i,1] * B[j,i]
>> end
>> end
>>
>> On Mon, Sep 14, 2015 at 8:45 PM, Patrick Kofod Mogensen <
>> [email protected]> wrote:
>>
>>> Sorry, something went wrong with my description. It was supposed to be:
>>>
>>> C =A[2:end, 1]' .* B[:, 2:end]
>>>
>>> A is n-by-2 and B is n-by-n (difference!). So B[:, 2:end] is n-by-(n-1)
>>> and I expect C to be n-by-(n-1). Sorry for this mistakes!
>>>
>>>
>>>
>>> On Monday, September 14, 2015 at 8:39:59 PM UTC-4, Tom Breloff wrote:
>>>>
>>>> What size do you expect your result to be? Are you creating a 1 x
>>>> (b-1) row vector? If so, I would check out the ArrayViews package and do
>>>> something like:
>>>>
>>>> using ArrayViews
>>>> A1 = view(A,:,1)
>>>> C = Float64[dot(A1, view(B,:,i)) for in 2:size(B,2)]
>>>>
>>>> On Mon, Sep 14, 2015 at 7:27 PM, Patrick Kofod Mogensen <
>>>> [email protected]> wrote:
>>>>
>>>>> I have a line in my code that seems to really allocate a lot of
>>>>> memory, and I think it might be slowing down my program. I have two
>>>>> matrices. The first matrix A is n-by-2 and the second matrix B is n-by-b.
>>>>> What I need to do is to multiply the first column of A element by element
>>>>> to each row in B[:, 2:end]. I use broadcasting (.*) to achieve this along
>>>>> with a transpose of A[:,1]:
>>>>>
>>>>> C=A[:,1]'.*B[:,2:end]
>>>>>
>>>>> However, it seems to allocate a lot of temporary memory (the number
>>>>> memory number in .mem overflows even for small problems). Is there
>>>>> anything
>>>>> I can do here?
>>>>>
>>>>>
>>>>> P
>>>>>
>>>>
>>>>
>>
