how can i write square root of mod x1(t)

sqrt(x(1)*t)

Answer 1

[John D'Errico]

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?