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Old 2019-06-19, 01:06   #1
tServo
 
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Default How does this compute

Can someone please explain how this Mod is computed?
TIA

Code:
(20:02) gp > (Mod(2633043,8388607)/9)
%1 = Mod(5884965, 8388607)
(20:02) gp > lift(%1)
%2 = 5884965]
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Old 2019-06-19, 01:15   #2
paulunderwood
 
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Quote:
Originally Posted by tServo View Post
Can someone please explain how this Mod is computed?
TIA

Code:
(20:02) gp > (Mod(2633043,8388607)/9)
%1 = Mod(5884965, 8388607)
(20:02) gp > lift(%1)
%2 = 5884965]
It computes 2633043 mod 8388607

Then 2633043/9 mod 8388607

Then "lifts" it to an integer.

It does the division by some kind of extended euclidian algorithm. Note that gcd(8388607,9)==1 must be so.

9 * 5884965 == 2633043 mod 8388607

That is 8388607 divides 9 * 5884965 - 2633043

Last fiddled with by paulunderwood on 2019-06-19 at 01:18
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Old 2019-06-19, 01:17   #3
hansl
 
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https://en.wikipedia.org/wiki/Modula...cative_inverse

Code:
? Mod(2633043,8388607)/9
%5 = Mod(5884965, 8388607)
? Mod(9,8388607)^-1
%6 = Mod(1864135, 8388607)
? Mod(1/9,8388607)
%7 = Mod(1864135, 8388607)
? Mod(2633043*1864135, 8388607)
%8 = Mod(5884965, 8388607)
?
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Old 2019-06-22, 14:48   #4
tServo
 
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Thanks ! I appreciate your time.
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