Re: problems with log function

[Stephen Leake <Stephe.Leake@nasa.gov>]

jsuarezrivaya@yahoo.es (Jorge Su?rez-Sol?s Rivaya) writes:

> hi, this is my first post.

Welcome!

> 
> First of all 'hi' to every body, my name is Jorge and Im from Spain.
> 
> I have a problem with the log function.
> 
> I have made an instantion of the generic package
> Ada.Numerics.Generic_Elementary_Function for Floats something like
> this:
> 
> package Math is new Ada.Numerics.Generic_Elementary_Function(Float);
> use Math;
> 
> and when i use it a say: log(Y)   
> Y is a float of course. I do not have any compilation problem, but
> when I execute it I get an Ada.Numerics.Argument_Error if Y is higher
> than 1.0

It helps if you post a compilable example to show your problem. Often
the problem is not what you think it is; having the real source lets
us see what is really going on for you.

Since this is your first post, and I'm on lunch break, I wrote one for
you:

with Ada.Numerics.Generic_Elementary_Functions;
with Ada.Text_Io; use Ada.Text_Io;
procedure Jorge
is
   package Math is new Ada.Numerics.Generic_Elementary_Functions (Float);
   use Math;

   X : Float;

begin
   Put_Line ("x     log (x)");
   for Y in 1 .. 10 loop
      X := 0.2 * Float (Y);
      Put_Line (Float'Image (X) & "  " & Float'Image (Log (X)));
   end loop;

end Jorge;

Compiling and running this with GNAT 5.01a on Windows 2000, I get:

make -r jorge.run
gnatmake -k -O3 -gnatn -gnatwa -I.. jorge -largs   -bargs  -cargs 
gcc -c -I./ -O3 -gnatn -gnatwa -I.. -I- ..\jorge.adb
gnatbind -aO./ -I.. -I- -x jorge.ali
gnatlink jorge.ali
./jorge.exe 
x     log (x)
 2.00000E-01  -1.60944E+00
 4.00000E-01  -9.16291E-01
 6.00000E-01  -5.10826E-01
 8.00000E-01  -2.23144E-01
 1.00000E+00   0.00000E+00
 1.20000E+00   1.82322E-01
 1.40000E+00   3.36472E-01
 1.60000E+00   4.70004E-01
 1.80000E+00   5.87787E-01
 2.00000E+00   6.93147E-01

I didn't check the numbers, but I assume they are correct. In any
case, no constraint errors.

It may be that log is actually broken on your platform; please tell us
what compiler and operating system you are using.

Hope this helps.

-- 
-- Stephe