Symbolic computation ERROR?

p=sym('5744092954902128823202697');
randi([2,p-2])

So I've defined p and tried to compute randi([2,p-2]), Matlab returns: 'Size and range inputs must be numeric.'.

I know it's something to do with the symbolic variable but I do not know why this is happening, nor the solution. Is there a way to do this without converting p to numeric because I don't want to lose precision

THANK YOU!

Answer 1

[Walter Roberson]

Rsymproc = feval(symengine, 'random', p-3);
Rsym = @() feval(symengine, Rsymproc) + 1;

Now each call to Rsym() will return one random number in the range [2, p-2]

Note: the internal procedure generated for this does not accept array sizes, so to generate multiple values, call Rsym multiple times.

[Yuechuan Chen]

So using the information you've provided I did

Rsymproc = feval(symengine, 'random', p-3);
Rsym = @() feval(symengine, Rsymproc) + 2;
feval(symengine, Rsym)

which looks legit, is this right?

[Yuechuan Chen]

So my interpretation is that Rsymproc generates a random integer in the range [0,p-4], and Rym increases the minima&maxima by 2 so it becomes [2,p-2], and feval just outputs the number generated.

I tried this with p=7 and q=3 and it seemed correct.

[Walter Roberson]

You do not need to

feval(symengine, Rsym)

You can just

Rsym()

You are correct in your intepretation of how the functions work.