# user6818

 1d comment Doing vector manipulations on MathematicaNo..it didn't work..you can see this question that I put up about this, mathematica.stackexchange.com/questions/25696/… 1d asked Doing vector manipulations in Mathematica (Part 2) 1d comment "wakeup" doesn't workAfter I copy-paste your code into the terminal it asks for [sudo] password and after putting in my password (the same which unlocks the computer?) it says, "patch: **** Can't open patch file /dev/fd/63 : No such file or directory" What is this? 1d asked "wakeup" doesn't work 1d comment Doing vector manipulations on MathematicaCan this ":>" replacement trick be generalized to other cases as well? Like if I want to replace any occurrence of $2\vec{q}.\vec{k}$ by $\vert \vec{q} +\vec{k} \vert ^2 - q^2 - k^2$? (or to even start can I input a function with vector inner products? - algebraically and not with specific numbers and then do the above kind of replacement?) May 19 comment Doing vector manipulations on MathematicaMore than that this is part of the definition of what is "Norm" of a vector. Why isn't this already known to Mathematica!? How else does one define Norm!? May 19 comment Doing vector manipulations on MathematicaBut conceptually its just one concept that the Norm of a negative of a vector is the same as the Norm of the vector. Can't this be made into just one rule to be specified? May 19 comment Doing vector manipulations on Mathematica(..if it does all that a human would do with vector norms then I can go ahead use your script for various such large manipulations I would want to do - if the Norm factors are not combining well then I would have sieve through hundred of such expressions to pick by hand all the factors correctly!..) May 19 comment Doing vector manipulations on MathematicaGreat that there is a site like this! Its just impossible to know so many "tricks" with a software every time one has to do something - which is trivial to do by hand! So your "myform" specification also takes care of thinks like converting Norm[-x-y] to Norm[x+y] or Norm[x-y] to Norm[y-x] and all such possible combinations? May 19 comment Doing vector manipulations on MathematicaThanks! Thats quite sophisticated! So you are basically putting in an extra rule to convert Norm[-x+y] to Norm[x-y]. But how does Mathematica understand this to convert Nor[-q] to Norm[q]? Does it on its own put a $0$ vector for the blank slot of y? May 19 comment Doing vector manipulations on MathematicaI had to put in Norm[-k2-q] and Norm[-q] intentionally to cause at least some simplification! Otherwise even those would have been messed! May 19 comment Doing vector manipulations on Mathematica@SimonWoods You can see this example - like if you put in, (F2s[q, k1]*F2s[-q, k2] F2s[k2 + q, k2 + k1])*(Norm[-q]^n Norm[-k1 + q]^n*Norm[-k2 - q]^n) // Expand // TraditionalForm then one can see that in various terms Norm[-q] and Norm[q] haven't been combined - hoping that everything else has worked out right! May 19 comment Doing vector manipulations on Mathematica@SimonWoods That does seem to help but it still doesn't seem to "understand" what a vector is. Like if I now evaluate F2s[p1,-k2] then it gives the answer in terms of stuff like Norm[-k2] - it doesn't understand that Norm[-k2] = Norm[k2]. Also once I have defined what what the function F2s is I want to be to able to evaluate the function on any combination of vectors like say F2s[k2+p1,k2+k1] wher k2, k1 and p1 are all vectors - how can this be done? I want it to behave like a function which takes two vectors and gives me its square/cube etc in the form I explained May 18 comment Doing vector manipulations on Mathematica@bills I have added more details into the question. I guess now the question is more clear about what I want. May 18 comment Doing vector manipulations on MathematicaYou can see the edits that I made in the question. I guess now I have made my question more clear about what I want. It would be great if you can help! May 18 revised Doing vector manipulations on Mathematicaadded 908 characters in body May 18 comment Doing vector manipulations on Mathematica@bills Didn't get you. $F_2^{(s)}$ function is as defined in equation A.3 on page 19 of my linked paper. I want to be able to say take the square of it. How do I do it? May 17 comment Doing vector manipulations on MathematicaI guess my question isn't well-framed. I didn't ask for such a thing. I am looking for an algebraic answer - and not for specific vectors you plugged in for $q1$ and $q2$. I can by hand calculate everything for general vectors - I guess there should be a way to do it in Mathematica also! May 17 comment Doing vector manipulations on Mathematica@Jens Like, could tell me how I can get Mathematica to calculate say $(F_2^{(s)}(\vec{k},\vec{k}-\vec{q}))^2$ ? .. for example..or if you could help solve the previous question linked from here.. May 17 asked Doing vector manipulations on Mathematica