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Explore Stack InternalThis is how I would write it:
sneakydeterminant[m_] := sneakydeterminant[m] = sneakydeterminant[Transpose[m]] = If[Length[m] == 1, m[[1, 1]]], Sum[Power[-1, j + 1] m[[1, j]] sneakydeterminant[ m[[Complement[Range[Length[m]], {1}], Complement[Range[Length[m]], {j}]]]], {j, 1, Length[m]}] ] The only difference is the time at which the new DownValue is added, but it should be equally safe.
This is how I would write it:
sneakydeterminant[m_] := sneakydeterminant[m] = sneakydeterminant[Transpose[m]] = If[Length[m] == 1, m[[1, 1]]], Sum[Power[-1, j + 1] m[[1, j]] sneakydeterminant[ m[[Complement[Range[Length[m]], {1}], Complement[Range[Length[m]], {j}]]]], {j, 1, Length[m]}] ] The only difference is the time at which the new DownValue is added, but it should be equally safe.
This is how I would write it:
sneakydeterminant[m_] := sneakydeterminant[m] = sneakydeterminant[Transpose[m]] = If[Length[m] == 1, m[[1, 1]]], Sum[Power[-1, j + 1] m[[1, j]] sneakydeterminant[ m[[Complement[Range[Length[m]], {1}], Complement[Range[Length[m]], {j}]]]], {j, 1, Length[m]}] The only difference is the time at which the new DownValue is added, but it should be equally safe.
This is how I would write it:
sneakydeterminant[m_] := sneakydeterminant[m] = sneakydeterminant[Transpose[m]] = Module[{answer}, If[Length[m] == 1, m[[1, 1]]], Sum[Power[-1, j + 1] m[[1, j]] sneakydeterminant[ m[[Complement[Range[Length[m]], {1}], Complement[Range[Length[m]], {j}]]]], {j, 1, Length[m]}] ] ]; The only difference is the time at which the new DownValue is added, but it should be equally safe.
This is how I would write it:
sneakydeterminant[m_] := sneakydeterminant[m] = sneakydeterminant[Transpose[m]] = Module[{answer}, If[Length[m] == 1, m[[1, 1]]], Sum[Power[-1, j + 1] m[[1, j]] sneakydeterminant[ m[[Complement[Range[Length[m]], {1}], Complement[Range[Length[m]], {j}]]]], {j, 1, Length[m]}] ] ]; The only difference is the time at which the new DownValue is added, but it should be equally safe.
This is how I would write it:
sneakydeterminant[m_] := sneakydeterminant[m] = sneakydeterminant[Transpose[m]] = If[Length[m] == 1, m[[1, 1]]], Sum[Power[-1, j + 1] m[[1, j]] sneakydeterminant[ m[[Complement[Range[Length[m]], {1}], Complement[Range[Length[m]], {j}]]]], {j, 1, Length[m]}] ] The only difference is the time at which the new DownValue is added, but it should be equally safe.
This is how I would write it:
sneakydeterminant[m_] := sneakydeterminant[m] = sneakydeterminant[Transpose[m]] = Module[{answer}, If[Length[m] == 1, m[[1, 1]]], Sum[Power[-1, j + 1] m[[1, j]] sneakydeterminant[ m[[Complement[Range[Length[m]], {1}], Complement[Range[Length[m]], {j}]]]], {j, 1, Length[m]}] ] ]; The only difference is the time at which the new DownValue is added, but it should be equally safe.