Here is the first invmod method
invmod=: 4 : 0
NB. inverse of y mod x (x|y)
NB. uc vc ud vd d c where d c init as x y
NB. q =. d<.@%c -- (4&{ <.@%~ {:)
a=. imw^:_ ] 1x,0x,0x,1x,x,y
if. 1~: 4{a do. 0 return. end.
if.0< 2{ a do. 2{ a else. x+2{a end.
)
imw =: ((2&{ - {. * 4&{ <.@% {:),(3&{ - 1&{ * 4&{ <.@% {:), 2&{., ({: | 4&{)
,~{:)^:(0 ~: {:)
testinvmod =: (0 1 e.~ [ | ]* invmod)
11 invmod 3
4
(14114588 +i.10) ( invmod)"0 1 ] 3x
4704863 0 9409727 4704864 0 9409729 4704865 0 9409731 4704866
ts '(14114588x +i.10000) (testinvmod )"0 ] 3x'
2.74558/sec 3.14547MB
ts '(14114588 +i.10000) (invmod )"0 ] 3'
2.96905/sec 3.26822MB
----- Original Message -----
From: Pascal Jasmin <[email protected]>
To: "[email protected]" <[email protected]>
Cc:
Sent: Wednesday, January 29, 2014 11:35:19 AM
Subject: [Jprogramming] math requests
With all of the mathematicians on this list, these functions have likely been
implemented before in J.
elyptic curve point add, multiplication and double
a python reference implementation:
https://github.com/warner/python-ecdsa/blob/master/ecdsa/ellipticcurve.py
the functions are: __add__ __mul__ and double
if I may suggest J explicit signatures for the first 2 functions as:
F =: 4 : 0
'yx yy yo' =. y
'xx xy xo' =. x
)
Some other methods than the python reference could be considered here:
http://en.wikipedia.org/wiki/Elliptic_curve_point_multiplication
also appreciated if you have in implementation of inverse_mod
for reference function of same nate at:
https://github.com/warner/python-ecdsa/blob/master/ecdsa/numbertheory.py
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