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Khaled Hamed

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09 Feb 2010 Qudrivariate and pentavariate normal orthant probabilities Evaluate the qudrivariate and pentavariate normal distribution orthant probabilities Author: Khaled Hamed pentavariate normal, orthant probability, quadrivariate normal 3 0
02 Jul 2009 Text Twist Puzzle Solver Gives the solution of a Text Twist Puzzle Author: Khaled Hamed text twist, word games 3 0
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06 Aug 2009 Variable Precision Integer Arithmetic Arithmetic with integers of fully arbitrary size. Arrays and vectors of vpi numbers are supported. Author: John D'Errico

More fun with vpi2english if you use, for example,

speak(vpi2english(vpi(2^52)))

The function "speak" is summission File ID: #4769 named "Speak".

There are a also a couple more "speak" submissions around.

31 Jul 2009 Fractions Toolbox create and manipulate fractions (K+N/D) using exact arithmetic Author: Ben Petschel

Very useful toolbox, especially with the added precision of the vpi toolbox.

I think the demo_fr.m file needs an "echo on" at the beginning to see the header of each of the demo problems, rather than answers only (followed by echo off at the end).

31 Jul 2009 Fractions Toolbox create and manipulate fractions (K+N/D) using exact arithmetic Author: Ben Petschel

It seems to require vpi to be in the Matlab path, or a previous instance of a vpi.

>> fr(1,7)
??? Error using ==> superiorto
Unknown class 'vpi' listed in 'SUPERIORTO'.

Error in ==> fr.fr at 201
superiorto('vpi','double','single','int8','uint8','int16', ...

29 Jul 2009 Variable Precision Integer Arithmetic Arithmetic with integers of fully arbitrary size. Arrays and vectors of vpi numbers are supported. Author: John D'Errico

Another good reason to use higher preciesion: the famous subtractive cancellation error

>> x=77617;y=33096;z=33375*y^6+100*x^2*(11*x^2*y^2-y^6-121*y^4-2)+550*y^8

z = -1.5112e+023

>> x=sym(77617);y=sym(33096);z=33375*y^6+100*x^2*(11*x^2*y^2-y^6-121*y^4-2)+550*y^8

z = -200

>>x=vpa(77617);y=vpa(33096);z=100*x^2*(11*x^2*y^2-y^6-121*y^4-2)+33375*y^6+550*y^8

z = -200.0

>> x=vpi(77617);y=vpi(33096);z=33375*y^6+100*x^2*(11*x^2*y^2-y^6-121*y^4-2)+550*y^8

z = -200

vpi is as accurate as symbolic and vpa, roughly four times faster than sym and eight times faster than vpa

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10 Jan 2014 Text Twist Puzzle Solver Gives the solution of a Text Twist Puzzle Author: Khaled Hamed Ziko

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