Re: declaring a scalar

[Paul Roberts]

Ah yes. That is a good point. Octave will interpret the expression:

k + A

to mean that you want to add the scalar value of k to every element of
A, or k*ones(n) + A. This is different from the interpretation that k
+ A means k*eye(n) + A. I would argue however that the expression k +
A does not make much sense mathematically anyway.

Paul


On 4/9/07, Geordie McBain <address@hidden> wrote:
> Yes, most of the time, but a little catch (which can be difficult to
> debug) is that if k is a scalar, u a length n column vector, and A is an
> n*n matrix, then sometimes mathematically we think k*u + A*u is the same
> as (k+A)*u, but to get it in Octave we need (k*eye(n)+A)*u.
>
> On Sun, 2007-04-08 at 16:36 -0700, Paul Roberts wrote:
> > I believe that in octave, a 1x1 matrix is treated as a scalar, so you
> > may write your code assuming that if you say x=2, then the variable x
> > will behave like a scalar variable with value 2.
> >
> > Paul
> >
> > On 4/8/07, Vivek Rao <address@hidden> wrote:
> > > x = 2
> > >
> > > creates a 1-by-1 matrix. How can I create a scalar
> > > variable with value 2? Thanks.
> > >
> > > Vivek Rao