$ include "seed7_05.s7i";
  include "float.s7i";
  include "math.s7i";

const func float: agm (in var float: a, in var float: g) is func
  result
    var float: agm is 0.0;
  local
    const float: iota is 1.0E-7;
    var float: a1 is 0.0;
    var float: g1 is 0.0;
  begin
    if a * g < 0.0 then
      raise RANGE_ERROR;
    else
      while abs(a - g) > iota do
        a1 := (a + g) / 2.0;
        g1 := sqrt(a * g);
        a := a1;
        g := g1;
      end while;
      agm := a;
    end if;
  end func;

const proc: main is func
  begin
    writeln(agm(1.0, 2.0) digits 6);
    writeln(agm(1.0, 1.0 / sqrt(2.0)) digits 6);
  end func;