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Re: IDL inverse matrix problem?? [message #90067 is a reply to message #90065]

Thu, 22 January 2015 12:36

wlandsman
Messages: 743
Registered: June 2000

Senior Member

On Thursday, January 22, 2015 at 2:24:06 PM UTC-5, Amin Farhang wrote:

> As you see this time IDL return the inverse BUT this inverse is WRONG!!!
> Let me test the IDL inversion:
>
> IDL> Bm = Am ## Am2
> IDL> print,Bm
> 0.99999999 -1.3038516e-08 -5.5879354e-09 -4.4703484e-08 4.4703484e-08
> -7.4505806e-09 1.0000000 1.8626451e-09 -4.4703484e-08 5.9604645e-08 -7.4505806e-09 -7.4505806e-09 0.99999999 -8.9406967e-08 1.1920929e-07
> -7.4505806e-09 -1.1175871e-08 -7.4505806e-09 0.99999994 1.7881393e-07
> -7.4505806e-09 -1.1175871e-08 -4.6566129e-09 -1.1920929e-07 1.0000001
>
> As you see the returned matrix is not a identity matrix, therefore the inversion is wrong.

Are you sure this is wrong? It looks like diagonal elements [0.99999999, 1.0000000, 0.99999999 ...] are equal to 1 within roundoff error, and the non-diagonal elements are all less 1.2d-7. So within roundoff error this appears to be the identity matrix. --Wayne

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[Message index]

		IDL inverse matrix problem?? By: amin farhang on Thu, 22 January 2015 11:24
		Re: IDL inverse matrix problem?? By: wlandsman on Thu, 22 January 2015 12:36
		Re: IDL inverse matrix problem?? By: amin farhang on Thu, 22 January 2015 13:00
		Re: IDL inverse matrix problem?? By: Craig Markwardt on Thu, 22 January 2015 13:40
		Re: IDL inverse matrix problem?? By: amin farhang on Thu, 22 January 2015 22:58
		Re: IDL inverse matrix problem?? By: chris_torrence@NOSPAM on Fri, 23 January 2015 07:25
		Re: IDL inverse matrix problem?? By: Craig Markwardt on Fri, 23 January 2015 10:32
		Re: IDL inverse matrix problem?? By: amin farhang on Fri, 23 January 2015 10:32
		Re: IDL inverse matrix problem?? By: chris_torrence@NOSPAM on Fri, 23 January 2015 10:56
		Re: IDL inverse matrix problem?? By: Craig Markwardt on Fri, 23 January 2015 11:50
		Re: IDL inverse matrix problem?? By: amin farhang on Fri, 23 January 2015 11:56
		Re: IDL inverse matrix problem?? By: chris_torrence@NOSPAM on Fri, 23 January 2015 12:06
		Re: IDL inverse matrix problem?? By: wlandsman on Fri, 23 January 2015 12:08
		Re: IDL inverse matrix problem?? By: amin farhang on Fri, 23 January 2015 12:00
		Re: IDL inverse matrix problem?? By: amin farhang on Fri, 23 January 2015 12:06
		Re: IDL inverse matrix problem?? By: chris_torrence@NOSPAM on Fri, 23 January 2015 12:28
		Re: IDL inverse matrix problem?? By: David Fanning on Fri, 23 January 2015 12:35

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