picomath

generic
    type Float_Type is digits <>;
package Expm1 is

    function Expm1(x: Float_Type'Base) return Float_Type'Base;

end Expm1;

with Ada.Numerics.Generic_Elementary_Functions;

package body Expm1 is

    package Elementary_Functions is new Ada.Numerics.Generic_Elementary_Functions(Float_Type'Base);
    use Elementary_Functions;

    function Expm1(x: Float_Type'Base) return Float_Type'Base is

    begin
        if Abs(x) < 1.0e-5 then
            return x + 0.5 * x * x;
        else
            return Exp(x) - 1.0;
        end if;
    end Expm1;

end Expm1;