Comments on: Decomposing Matrices

By: Rachel 'Groby' Blum

Rachel 'Groby' Blum — Wed, 24 Jun 2009 12:25:10 +0000

Hey Aaron – you are perfectly right. It’s amazing how many typos one can add transcribing math

By: Aaron

Aaron — Fri, 19 Jun 2009 23:01:38 +0000

I think there’s a mistake: rotation.y=asin( matrix._13 ) I think should be rotation.y=asin( -matrix._13 )

By: Andy Geers

Andy Geers — Sat, 09 May 2009 11:40:58 +0000

Assuming the description of how to apply the scaling is correct, then I think there's an error in your code: rotation.x = atan2( matrix._23scale.x, matrix._33 ); rotation.z = atan2( matrix._12scale.y, matrix._11 );

should really read as follows: rotation.x = atan2( matrix._23scale.z, matrix._33 ); rotation.z = atan2( matrix._12scale.x, matrix._11 );

... since you said you want to divide matrix._11 by scale.x and matrix._33 by scale.z

By: cb

cb — Thu, 16 Apr 2009 19:13:00 +0000

Are we there yet? Not quite! What if Cos(y) is zero?

Is there any way you could add code for this case, as well? Thanks!

By: Administrator

Administrator — Tue, 03 Jun 2008 14:05:06 +0000

@Bill: Indeed. Great catch. I’ve updated it

By: Administrator

Administrator — Tue, 03 Jun 2008 04:24:05 +0000

Thanks, Bill. Updated the article.

By: Bill

Bill — Thu, 29 May 2008 07:32:12 +0000

Hi, You wrote: "Staring a bit harder at the matrix, we find a nice pair of values in row 2&3, column 3: Sin(x).Cos(y) and Cos(x).Cos(y). If we divide those two, we get Sin(x)/Cos(x) = Tan(x)."

But the first pair of values is negative and so Tan(x) doesnt work this way....have you simply forgotten the minus sign? Thanks Bill

By: Rob

Rob — Wed, 05 Jul 2006 10:21:50 +0000

Just wonderful to find an xyz rotation matrix for reference.

By: Karsten Isakovic

Karsten Isakovic — Mon, 08 May 2006 07:38:28 +0000

There is a minor bug in your formlar for the matrix.32 - in the first term there should be a Sin(z) instead of Cos(z). So matrix.32 should read Cos(x).Sin(y).Sin(z) - Sin(x).Cos(z) .

By: Robert Blum

Robert Blum — Thu, 29 Sep 2005 15:52:51 +0000

Your wish is my command Hope that helps!