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TI-Basic => TI-BASIC
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vic9317

Newbie

Joined: 16 Nov 2008
Posts: 26

 Posted: 08 Nov 2010 06:20:05 pm    Post subject: I was asked a question that I can't seem to figure out concerning the row echelon form of a matrix and the ref( command. Take the following matrix [A], for example: [1 3 -5 ] [4 7 -10] [-2 2 3 ] Using ref([A])►Frac on it produces the following: [1 7/4 -5/2 ] [0 1   -4/11] [0 0   1    ] However, manually finding the row echelon form as well as using online solvers such as this one produces: [1 3 -5] [0 1 -2] [0 0  1] My question is: why? Does the calculator's method of finding the ref (which I presume is Gaussian elimination) different from the manual method? Are they both correct? Seems intriguing...
Weregoose
Authentic INTJ

Super Elite (Last Title)

Joined: 25 Nov 2004
Posts: 3976

 Posted: 09 Nov 2010 04:10:47 pm    Post subject: Safety measures included, this is the exact algorithm used by that solver to generate its matrices on the right hand side. dim([A]→L1 [A] For(U,1,min(L1 If not(Ans(U,U Pause rowSwap(Ans,U,U+1►Frac Pause *row(Ans(U,U)‾¹,Ans,U►Frac For(V,U+1,L1(1 If Ans(V,U Pause *row+(‾Ans(V,U),Ans,U,V►Frac End End That's all I can provide at this moment. It's been a long time since I've last worked with matrix operations.Last edited by Guest on 09 Nov 2010 04:11:55 pm; edited 1 time in total
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