Re: fast replace for matrix minor
- To: mathgroup at smc.vnet.net
- Subject: [mg69515] Re: [mg69476] fast replace for matrix minor
- From: "Carl K. Woll" <carlw at wolfram.com>
- Date: Thu, 14 Sep 2006 06:56:43 -0400 (EDT)
- References: <200609130803.EAA18423@smc.vnet.net>
Christopher Arthur wrote:
> Is there a quick way to replace a small minor block in a large matrix?
> Using ReplacePart in a Do loop seems to be very inefficient with
> respect to timing
>
> Chris Arthur
Something like this?
m=Array[Plus,{5,5}];
Replace minor block with rows 2,3,4 and columns 4 and 5:
m[[Range[2,4],Range[4,5]]] = {{a,b},{c,d},{e,f}};
Now, the matrix m has had a minor block replaced with the above matrix.
Carl Woll
Wolfram Research
- References:
- fast replace for matrix minor
- From: Christopher Arthur <caa0012@unt.edu>
- fast replace for matrix minor