Category Archives: Scientific Computing

Create a symmetric matrix in Mathematica

By Bojan | Published: November 18, 2009
Here is a quick way to create a symmetric matrix in Mathematica. The code below creates a generic 6×6 matrix (line 1), then mirrors the above-diagonal elements to their below-diagonal counterparts (substitution in lines 3-5). am = Array[Subscript[a,##] &, {6,6}]; am = am /. Flatten[Table[ Subscript[a,i,j] -> Subscript[a,j,i], {i,2,6}, {j,1,i-1}]]
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Function call counting in Matlab

By Bojan | Published: March 23, 2006
Here’s a neat way to keep track of the cost, i.e. number of function calls in Matlab: rather than using a counter variable and increment it each time a function is called, use the internal Matlab counters, accessible through the FunctionTable struct array. The loop below is necessary only to get the index of the [...]
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