I have a function where a n parameter is handed and a list of values is calculated inside of it. I then need to solve a linear system of equations that require me to construct a n x n matrix where the first row is only 1's the second row is the calculated list in a row and the following rows are this list raised to power i, where i=2,...,n.
Example:
n=4; list={2,3,5,4};
m = {{1, 1, 1, 1}, {2,3,5,4}, {4, 9, 25, 16}, {8,27,125,64}};
Define
f[n_,list_] := Table[ list^k, {k,0,n-1} ]
so that f[3,{2,3,4}] produces {{1,1,1},{2,3,4},{4,9,16}}.
If list can contain zeros, use the following instead:
f[n_, list_] :=
Table[If[k == 0, ConstantArray[1, Length@list], list^k], {k, 0,
n - 1}]
or, to avoid to have it do a check at every iteration,
f[n_, list_] := Join[{ConstantArray[1,Length@list]},Table[list^k,{k,1,n-1}]]
list has a zero in it.
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Commented
Dec 7, 2015 at 19:46
k == 0 every time, I would have done something like Prepend[Table[list^k, {k, n}], ConstantArray[1, Length@list]] to avoid the If.
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Commented
Dec 7, 2015 at 19:55
If more clear. But of course you are right it is useless to have it do the check every time
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Manipulator[Dynamic[n], {2, 10,1}]
Dynamic[list2 = list^# & /@ Range[0, n-1]]
ishould be a power of two from1ton? That would fit with what he has. $\endgroup$Dynamicexpression, or do you just mean that the size of the matrix should change when you feed the function a differentn? $\endgroup$