Re: Why does Inverse[M] hesitate?

*To*: mathgroup at smc.vnet.net*Subject*: [mg54390] Re: Why does Inverse[M] hesitate?*From*: David Bailey <dave at Remove_Thisdbailey.co.uk>*Date*: Sun, 20 Feb 2005 00:07:49 -0500 (EST)*References*: <cv6t0c$6re$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Skirmantas wrote: > The Inverse function sometimes calculates the inverse of a matrix > immediately, sometimes it does not. Try this example in Mathematica > 5.1: > > A={{(1-g)-1,1},{-w P(1-g)/C,-1}}//MatrixForm > B={{0},{-P(w+1)}}//MatrixForm > > I get > Out: Inverse[(expanded A)].(expanded B) > > If I do just > A={{a,b},{c,d}} > B={{e},{f}} > Inverse[A].B > > I get the final correct result. > If you write A= <some matrix expression> //MatrixForm it displays beautifully, but the expression assigned to A actually contains the MatrixForm! You can check this by looking at FullForm[A]. You should write A=<some matrix expression>; A//MatrixForm That way the expression containing the MatrixForm gets discarded. BTW - This example just goes to show how useful it is to include ACTUAL CODE with a query! David Bailey dbaileyconsultancy.co.uk

**Follow-Ups**:**Re: Re: Why does Inverse[M] hesitate?***From:*DrBob <drbob@bigfoot.com>