Skip to main content

list manipulation - Optimize inner loops


I'm Mathematica newbie so please be gentle :) I have this, heavily non-optimized part of code, which I would like to speed up. I have put all matrices to be RandomReal, but in my code they take specific values. Also, matrices mat3, mat4, mat6 and mat7 consist of random simple trigonometric functions. Any kind of help is much appreciated. I have read about Map, Table, Do, Functional Programming... but I don't know how to apply it.


Code is part of Finite element-Finite strip calculation. I don't mind losing computing time during "real" calculation, but this part of code is just placing elements of matrices into other places with just few calculations. Matrices mat2, mat5, mat9, mat10 and mat11 need to be stored for later data processing.


Bonus question: is it possible to Compile this part of code?


Hope I gave optimal amount of data about my problem


All the best, Aleksandar



limit1 = 10;
limit2 = 20;
limit3 = 10;
limit4 = 15;
mat1 = RandomReal[{-100, 100}, {limit3, 2}];
mat2 = RandomReal[{-100, 100}, {limit1, limit2, limit3, 2}];
mat3 = Table[Sin[m*\[Pi]*y] + Cos[s*\[Pi]*y], {m, limit2}, {s, limit3}];
mat4 = Table[Sin[m*s*\[Pi]*y] + Cos[s*\[Pi]*y], {m, limit2}, {s, limit3}];
mat5 = RandomReal[{-100, 100}, {limit1, limit2, limit3, 6}];
mat6 = Table[Sin[m*m*\[Pi]*y] + Cos[s*\[Pi]*y], {m, limit2}, {s, limit3}];

mat7 = Table[Sin[m*\[Pi]*y] + Cos[s*s*\[Pi]*y], {m, limit2}, {s, limit3}];
mat8 = RandomReal[{-100, 100}, {limit2, limit3, limit4, 2}];
mat9 = RandomReal[{-100, 100}, {limit1, limit2, limit3, limit4}];
mat10 = RandomReal[{-100, 100}, {limit1, limit2, limit3, limit4}];
mat11 = RandomReal[{-100, 100}, {limit1, limit2, limit3, limit4}];

For[n = 1, n < limit1 + 1, n++,
For[i = 1, i < limit2 + 1, i++,

For[j = 1, j < limit3 + 1, j++,


y = (mat1[[j, 1]] + mat1[[j, 2]])/2;

mat2[[n, i, j, 1]] = mat3[[i, j]];

mat2[[n, i, j, 2]] = mat4[[i, j]];

mat5[[n, i, j, All]] = 1/2 (mat6[[i, j]] + mat7[[i, j]]);

Clear[y];


For[k = 1, k < limit4 + 1, k++,

zz = 1/2 (mat8[[i, j, k, 1]] + mat8[[i, j, k, 2]]);

mat9[[n, i, j, k]] = {mat5[[n, i, j, 1]] + zz*mat5[[n, i, j, 4]], 
                      mat5[[n, i, j, 2]] + zz*mat5[[n, i, j, 5]], 
                      mat5[[n, i, j, 3]] + zz*mat5[[n, i, j, 6]]};
mat10[[n, i, j, k]] = mat11[[n, i, j, k]].mat9[[n, i, j, k]];


Clear[zz]
]

]]
]


Comments

Post a Comment

Popular posts from this blog

mathematical optimization - Minimizing using indices, error: Part::pkspec1: The expression cannot be used as a part specification

I want to use Minimize where the variables to minimize are indices pointing into an array. Here a MWE that hopefully shows what my problem is. vars = u@# & /@ Range[3]; cons = Flatten@ { Table[(u[j] != #) & /@ vars[[j + 1 ;; -1]], {j, 1, 3 - 1}], 1 vec1 = {1, 2, 3}; vec2 = {1, 2, 3}; Minimize[{Total@((vec1[[#]] - vec2[[u[#]]])^2 & /@ Range[1, 3]), cons}, vars, Integers] The error I get: Part::pkspec1: The expression u[1] cannot be used as a part specification. >> Answer Ok, it seems that one can get around Mathematica trying to evaluate vec2[[u[1]]] too early by using the function Indexed[vec2,u[1]] . The working MWE would then look like the following: vars = u@# & /@ Range[3]; cons = Flatten@{ Table[(u[j] != #) & /@ vars[[j + 1 ;; -1]], {j, 1, 3 - 1}], 1 vec1 = {1, 2, 3}; vec2 = {1, 2, 3}; NMinimize[ {Total@((vec1[[#]] - Indexed[vec2, u[#]])^2 & /@ R...
Post a Comment
Read more

functions - Get leading series expansion term?

Given a function f[x] , I would like to have a function leadingSeries that returns just the leading term in the series around x=0 . For example: leadingSeries[(1/x + 2)/(4 + 1/x^2 + x)] x and leadingSeries[(1/x + 2 + (1 - 1/x^3)/4)/(4 + x)] -(1/(16 x^3)) Is there such a function in Mathematica? Or maybe one can implement it efficiently? EDIT I finally went with the following implementation, based on Carl Woll 's answer: lds[ex_,x_]:=( (ex/.x->(x+O[x]^2))/.SeriesData[U_,Z_,L_List,Mi_,Ma_,De_]:>SeriesData[U,Z,{L[[1]]},Mi,Mi+1,De]//Quiet//Normal) The advantage is, that this one also properly works with functions whose leading term is a constant: lds[Exp[x],x] 1 Answer Update 1 Updated to eliminate SeriesData and to not return additional terms Perhaps you could use: leadingSeries[expr_, x_] := Normal[expr /. x->(x+O[x]^2) /. a_List :> Take[a, 1]] Then for your examples: leadingSeries[(1/x + 2)/(4 + 1/x^2 + x), x] leadingSeries[Exp[x], x] leadingSeries[(1/x + 2 + (1 - 1/x...
Post a Comment
Read more

What is and isn't a valid variable specification for Manipulate?

I have an expression whose terms have arguments (representing subscripts), like this: myExpr = A[0] + V[1,T] I would like to put it inside a Manipulate to see its value as I move around the parameters. (The goal is eventually to plot it wrt one of the variables inside.) However, Mathematica complains when I set V[1,T] as a manipulated variable: Manipulate[Evaluate[myExpr], {A[0], 0, 1}, {V[1, T], 0, 1}] (*Manipulate::vsform: Manipulate argument {V[1,T],0,1} does not have the correct form for a variable specification. >> *) As a workaround, if I get rid of the symbol T inside the argument, it works fine: Manipulate[ Evaluate[myExpr /. T -> 15], {A[0], 0, 1}, {V[1, 15], 0, 1}] Why this behavior? Can anyone point me to the documentation that says what counts as a valid variable? And is there a way to get Manpiulate to accept an expression with a symbolic argument as a variable? Investigations I've done so far: I tried using variableQ from this answer , but it says V[1...
Post a Comment
Read more