# User Portlet Hans Dolhaine
Discussions
Hello Matheus 1) I suggest NOT to use variables with subscripts, that may lead to problems 2) What is sol? Without sol your matrix rho is not defined 3) Here ( I arbritarily define a matrix rho ) is some code which seems to do what you...
Hello Madeleine, perhaps something like this? coeff = .4; (* "Diffusion" constant *) nS = 100; (* number of sites *) nT = 150; (* number of time - steps *) m = Table[0, {nS}]; m[] = 1; (* magnetisation *) ...
Hello Karl, 1) I suggest that you rescale your problem to get rid of these nasty powers of ten. You can plot your problem from 2.5 to 2.8 rembering to apply a factor of 10^(-7) later on. 2) What do you mean by gaussian function? A normal...
I did some more work on this problem. See the attached notebook.
nc was intended to count the different sums. For the time being it is not important. Concerning your question and using Rohit's method sum = 0; sums = Table[ sum = sum + a[i][j]*If[j == 2, 0, 1], {i, 1, 3}, {j, 1, 3}] // ...
It is not quite clear to me what you want to do. If Amn etc. are your variables you can get the appropriate matrix mat by eq1 = (A11 Amn \[Alpha]^2 + C11 Dmn \[Alpha]^2 - B11 Cmn \[Alpha]^3 + A12 Bmn \[Alpha] \[Beta] + A66 Bmn...
I am afraid I don't understand your problem. What do you think about this? mm = Partition[RandomReal[{0, 10}, 9], 3]; mm // MatrixForm ev = Transpose[Eigenvectors[mm]]; ev // MatrixForm dia = Inverse[ev].mm.ev // Chop; ...
I think this could help num = {3, 10, 5, 16, 8, 0.01, 4, 2, 1, 77, 18, 92, 4, 100}; exp = 10^# & /@ (Log[10, N[num]] // IntegerPart) num[[#]] & /@ Position[IntegerPart[num/exp], 1] // Flatten
But if those c's are independent of your unknown c's you may want to know if there exists a unique and exact solution for your problem. In this case define a modified (augmented) matrix mm2 = Transpose[Join[Transpose[mat], {vec}]]; ...
Ok, but I think it should be the other way round because the question was x cos[y] dx+ sin x dy=0 : DSolve[y'[x] == (x Cos[y[x]])/Sin[x], y[x], x]