Re: polyval discussion

[Ben Abbott]

On Jul 23, 2011, at 12:30 PM, Robert T. Short wrote:

> I have some questions about polyval.  Depending on the outcome of this 
> discussion I will submit patches as necessary.
> 
> -----------------------
> First, a MATLAB compatibility issue.
> 
> If we have a matrix
> 
> p = [ [ 1 2 ];
>         [ 3 4 ] ];
> 
> and we attempt to evaluate p
> 
> p = polyval(p,1)
> 
> octave errors - p must be a vector.  MATLAB on the other hand returns
> 
> p = 4
> 
> MATLAB seems to use the first column as the polynomial.
> 
> Personally, I think the MATLAB approach makes no sense, but should polyval 
> emulate MATLAB?
> 
> -----------------------
> Second, here is what I would REALLY like polyval to do.
> 
> If p is a matrix, I would like polyval to return a vector in which each row 
> is treated as a polynomial.  That is, for the example above,
> 
> p = polyval(p,1)
> 
> would return
> 
> p= [3;7]
> 
> The modifications to polyval to do this are very simple but this is decidedly 
> not MATLAB compatible.
> 
> I could submit a new function, say mpolyval, but the new function would be a 
> near clone of polyval.

Might using cell array for the multiplicity of coefficients be a better idea?

Using cells should be easy to parse without introducing an incompatibility with 
Matlab.

Ben