Polynomial Menu - HP 40gs User Manual

hp40g+.book Page 55 Friday, December 9, 2005 1:03 AM
SUBTMOD

Polynomial menu

EGCD
Computer Algebra System (CAS)
Performs a subtraction in Z/pZ or Z/pZ[X].
Example 1
Typing:
SUBTMOD(29, 8)
gives:
–5
Example 2
Typing:
SUBTMOD(11X + 5, 8X + 6)
gives:
3x 1 –
Returns Bézout's Identity, the Extended Greatest Common
Divisor (EGCD).
EGCD(A(X), B(X)) returns U(X) AND V(X) = D(X), with D,
U, V such that D(X) = U(X)·A(X) + V(X)·B(X).
Example 1
Typing:
2
EGCD(X + 2 · X + 1, X
gives:
1 – 1 – = 2x + 2
AND
Example 2
Typing:
2
EGCD(X + 2 · X + 1, X
gives:
( )
– x 2 – 1 = 3x
AND
2
– 1)
3
+ 1)
+ 3
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