26 lines
587 B
APL
26 lines
587 B
APL
∇ R←M COMBIN N;D;E;F;G;P
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⍝ Returns a matrix of every possible
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⍝ combination of M elements from the
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⍝ vector ⍳N. That is, returns a
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⍝ matrix with M!N rows and N columns.
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⍝
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E←(⍳P←N-R←M-1)-⎕IO
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D←R+⍳P
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R←(P,1)⍴D
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P←P⍴1
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L1:→(⎕IO>1↑D←D-1)⍴0
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P←+\P
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G←+\¯1↓0,F←⌽P
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E←F/E-G
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R←(F/D),R[E+⍳⍴E;]
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E←G
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→L1
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∇
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∇ R←M QUICKEXP N
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⍝ Matrix exponentiation
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B ← ⌊ 1 + 2 ⍟ N
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V ← (B ⍴ 2) ⊤ N
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L ← ⊂ M
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R ← ⊃ +.× / V / L ⊣ { L ← (⊂ A +.× A ← ↑L) , L }¨ ⍳ B-1
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∇
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