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From: David C. Hoos, Sr. <david.c.hoos.sr@ada95.com>
Subject: Re: Problem with pragmas
Date: 1999/06/30
Message-ID: <7ldqh0$nbq$1@nnrp1.deja.com>#1/1
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References: <FE4vxK.20D@robkaos.ruhr.de>
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Date: 1999-06-30T00:00:00+00:00
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In article <FE4vxK.20D@robkaos.ruhr.de>,
  robsch@robkaos.ruhr.de (Robert Schien) wrote:
> I need to access the erf (Gaussian error function) from the C-Math-
Library.
> But the following program does not work correctly:
>

What you missed was that the type of the parameters is not C_Float,
but Double.

The following version of your program works correctly, and eliminates
the need for the -largs on the command line, as well.

with Ada.Float_Text_IO;
use  Ada.Float_Text_IO;
with Ada.Text_IO;
use  Ada.Text_IO;
with Interfaces.C;
use  Interfaces.C;

procedure Pragtest is
   pragma Linker_Options ("-lm");
   Y: Float;
   C_Y: Double;

   -- Accessing Gaussian error function
   function Erf (X: in Double) return Double;
   pragma Import(C,Erf);

begin
   Y:=0.3;
   C_Y:=Double(Y);
   C_Y:=Erf(C_Y);
   Y:=Float(C_Y);
   Put(Y);
end Pragtest;


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