Huh? It looks like you already know how to write sqrt(x(1)*t). So what is your question?
Are you looking to find a modular square root? Something else? For example, if you are working in the integers modulo n, the square root of a number x is defined as the number y such that
mod(y*y,n) = mod(x,n)
You can find modroot in my VPI toolbox. Or, you can write the code for the Shanks-Tonelli algorithm.
modroot(vpi(13437),100003)
ans =
643
mod(643^2,100003)
ans =
13437
Or, are you looking for something completely different?