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>