Evaluate a polynomial at an element

[Jonas Ehrhard]

I feel a bit stupid for asking this, but say I have a polynomial f over a field K, is it possible to evaluate f at some element a of K, i.e. compute f(a)? I was not able to do this, and did not find anything in the beginner tutorials.

[Mike Cummings]

Use the `sub` command. For example:

i1 : R = QQ[x,y];
i2 : f = x+y;
i3 : sub(f, y=>1)  -- evaluates f(x,1)
o3 = x + 1

[Torrance, Douglas]

Square brackets also work as syntactic sugar for "sub". For example:

i3 : f[x, 1]

o3 = x + 1

o3 : R

i4 : f[2, 3]

o4 = 5

[Jonas Ehrhard]

Thank you two, that is helpful!