Attempting to use complex variable results in input array non-numeric error for polyval

Say I have polynomial coefficients saved as

G11 = [1, 2, 3, 4];

and I wish to call polyval on said coefficients, except the nomenclature is made up of different variables as GXY where X equals group and Y equals day

group = 1;
day = 1;

I can run

sprintf('G%g%g', group, day);
ans = 
    'G11'

but when I run it with polyval I get an error

polyval(sprintf('G%g%g', group, day), 1);
Error using filter
Invalid data type. Input arrays must be numeric or logical.

Error in polyval (line 56)
    y = filter(1,[1 -x],p);

I'm not sure how to provide an appropriate input for polyval. I have tried num2str and some other ideas. The reason I am doing this is because I have 6 polynomials to loop through to verify a value is out of a certain range before recording a final value.

Thanks

Answer 1

[Jan]

Of course neither the char vector 'G11' nor any tricks with num2str can solve the problem. But hiding indoices in the names of variables is a bad idea at all. See TUTORIAL: How and why to avoid EVAL .

Use an array and indices instead:

G{1, 1} = [1,2,3,4];
group   = 1;
day     = 1;

polyval(G{group, day}, 1);

Answer 2

[Jam]

Thanks for that Jan, worked like a treat. Need to make mistakes to learn I suppose. I hadn't quite connected my "relelvant variable naming" to indices so to speak.

Cheers,

J