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51 lines
1.2 KiB
Plaintext
51 lines
1.2 KiB
Plaintext
NAME
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pmod - integral power of an integer modulo a specified integer
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SYNOPSIS
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pmod(x, n, md)
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TYPES
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x integer
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n nonnegative integer
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md integer
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return integer
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DESCRIPTION
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pmod(x, n, md) returns the integer value of the canonical residue
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of x^n modulo md, where the set of canonical residues is determined
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by md and bits 0, 2, and 4 of config("mod") (other bits are ignored).
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If md is zero, the value is simply x^n.
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For nonzero md, the canonical residues v modulo md are as follows:
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config("mod") md > 0 md < 0
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0 0 < v < md md < v < 0
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1 -md < v < 0 0 < v < -md
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4 0 < v < md 0 < v < -md
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5 -md < v < 0 md < v < 0
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16 -md/2 < v <= md/2 md/2 <= v < -md/2
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17 -md/2 <= v < md/2 md/2 < v <= -md/2
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20 -md/2 < v <= md/2 md/2 < v <= -md/2
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21 -md/2 <= v < md/2 md/2 <= v < -md/2
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EXAMPLE
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> c = config("mod",0)
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> print pmod(2,3,10), pmod(2,5,10), pmod(2,3,-10), pod(2,5,-10)
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8 2 -2 -8
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> c = config("mod",16)
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> print pmod(2,3,10), pmod(2,5,10), pmod(2,3,-10), pmod(2,5,-10)
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-2 2 -2 2
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LIMITS
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none
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LIBRARY
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NUMBER *qpowermod(NUMBER *x, NUMBER *n, NUMBER *md)
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SEE ALSO
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mod, minv
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