Module Checkit {
      Function Root (a, n%, d as double=1.e-4) {
             if n%=0 then Error "Division by zero: 1/0"
             if a<=0 then Error "Negative or zero number"
             if n%=1 then = a : exit
             Flush
             n2=1-1/n%:a/=n%:n%--:Push a
             {    Push 1: For i=1 to n% {Over 2 :Push Number*Number}
                  Over 2 : Push n2*Number + a/Number
                  Shift 2: Over 2, 2 :if Abs(Number-Number)>d Then loop
                  Drop
             }  Read a : = a
      }
      Print "square root single"
      Print root(1.3346767~, 2, 1.e-9)
      Print "square double"
      Print root(1.3346767, 2, 1.e-9)
      Print "square root decimal"
      Print root(1.3346767@, 2, 1.e-9)
      Print "internal square root, double"
      Print  1.3346767^(1/2)
      Print sqrt(1.3346767)
}
Checkit