Re: matrix
- To: mathgroup at smc.vnet.net
- Subject: [mg28397] Re: matrix
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Mon, 16 Apr 2001 03:28:49 -0400 (EDT)
- References: <9bb759$92p@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Continuiing on the line of Carl Woll's recent posting "Re: SpecialMatrix", it looks as if the following should be pretty efficient: Block[{mat = Take[IdentityMatrix[4000], All, 1220]}, mat[[All, All]] = 0; mat[[Range[216, 220], All]] = 1; mat]; -- Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 "Su Su Win" <susuwin at post.kek.jp> wrote in message news:9bb759$92p at smc.vnet.net... > Hello, > > How can I make a matrix (4000x1220) with zeros except that all the values at > 216th to 220th rows are ones. > Thank you very much in advance. > Regards, Win > > > >