Thanks, I'm starting to plan now, so I'm still confused with the production code, but what I need is to divide array 2x2 or 3x3. I still can not!
2012/11/12 Joshua Landau <joshua.landau...@gmail.com> > On 13 November 2012 01:00, Cleuson Alves <cleuso...@gmail.com> wrote: > >> Hello, I need to solve an exercise follows, first calculate the inverse >> matrix and then multiply the first matrix. >> > > This list isn't to give answers for homeworks, and this sounds like one. > We *do* give help to those who have a specific problem and who preferably > show that they are trying to help up help them. > > >> I await help. >> > > For what?! You haven't asked a question. > 1) What do you need. Answer precisely, preferably giving an example output > for the input you want > 2) What techniques have you tried? You have given code below in an > extremely un-obvious manner. What does it do, crash? Is it the wrong > output? What is wrong about the output? > 3) What do you *think* has gone wrong? What about the output seems to be > wrong? > > >> Thank you. >> follows the code below incomplete. >> > > On the basis that we can get some foreign people who maybe don't have > English as a commonly used language, muddled grammar isn't that big deal. > However, when asking for help it is worth checking that you've asked in a > clear way. > > >> m = [[1,2,3],[4,5,6],[7,8,9]] >> x = [] >> for i in [0,1,2]: >> y = [] >> for linha in m: >> y.append(linha[i]) >> x.append(y) >> >> print x >> [[1, 4, 7], [2, 5, 8], [3, 6, 9]] >> > > Is this the right output? Is this what you *meant* by inverse? As Ian > Kelly (who is undoubtedly more learned in this area) said, this is a > transpose, so you have just swapped the one axis with another. > > >> def ProdMatrix(x,b): >> tamL = len(x) >> tamC = len(x[0]) >> c = nullMatrix(tamL,tamC) >> for i in range(tamL): >> for j in range(tamC): >> val = 0 >> for k in range(len(b)): >> val = val + x[i][l]*b[k][j] >> c[i][j] >> return c >> > > You haven't given the full code. This crashes because we don't have > "nullMatrix" defined. It would be nice if we had something we could try to > run. > > Then, the error is: "NameError: global name 'l' is not defined". On the > line "val = val + x[i][l]*b[k][j]" you use a variable "l" which doesn't > exist. What should you be using, or should you have created it? > > *Then* you get an output of pure 0s. This is because you forgot to put > your result into c, your new matrix. > You probably just forgot to finish the line "c[i][j]", which does nothing > now. > > You're actually really close on the second part. I have no idea if you're > doing what you want for the first part, but it's not what's traditionally > called an inverse. > -- Cleuson de Oliveira Alves Rio de Janeiro - RJ
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