# How do I convert a table into a function?

If I have this table which produce a list of paires of numbers.

ref2A = Table[{x, GWR[fun2A, t0, NTerms, 0.001]}, {x, 0, nn, 0.005}]


How can I Calculate (plot)the function

f[x_, t_] := (-1 + Sqrt[1 + 2*k*ref2A[x, t]])/k


f[x_] = (-1 + Sqrt[1 + 2*k*Interpolation[ref2A][x]])/k;