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40 lines
670 B
Plaintext
40 lines
670 B
Plaintext
NAME
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comb - combinatorial number
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SYNOPSIS
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comb(x, y)
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TYPES
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x integer
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y integer
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return integer
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DESCRIPTION
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Return the combinatorial number C(x,y) which is defined as:
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x!
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---------
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y!*(x-y)!
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This function computes the number of combinations in which y things
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may be chosen from x items ignoring the order in which they are chosen.
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EXAMPLE
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> print comb(7,3), comb(7,4), comb(7,5), comb(3,0), comb(0,0)
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35 35 21 1 1
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> print comb(2^31+1,2^31-1)
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2305843010287435776
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LIMITS
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x >= y >= 0
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y < 2^24
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x-y < 2^24
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LIBRARY
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void zcomb(ZVALUE x, ZVALUE y, ZVALUE *res)
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SEE ALSO
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fact, perm
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