Here's another oldie which is probably not really needed these days. :)
We have an inbuilt SQRT() function which is probably faster and more accurate.
However, it's interesting to see how the iteration is used.
Note that it needs Double precision to work correctly ..
' Square Root by Iteration ..
' Calculating a Square Root using Iteration ..
z = 27 :' positive real number whose Square root is required
print "Square Root of ",z:print:print STRING$(30, "_" )
print:print:print "Iterations: ":print
x = z/2 :' arbitrary start value for the iteration
x = 0.5 * (x + z/x)
until ((x*x - z)/z <= 1.e-11) :' the test for convergence
print "The Square Root of ",z, " is ", x
' Compare with the inbuilt Sqrt() function ..
print "Using the CB Sqrt() Function, the result is .. ":print
print:print STRING$(30, "_" )
Best wishes, :)