Re: Why raises this an error? :-(

["Kai Gläsner" <Kai.Glaesner@t-online.de>]

Thanks for the quick Response.

The problem I have is, that the exponent is not an Integer (this was
just a test-example to find out what is wrong)

   <snip> 1.0 - (GetTemperature(The, Alt)/Temp) ** 0.2349690

Where GetTemperature() can return a value < 0.0.

But why is the value of the left operand not allowed to be negative
according to the ARM?

Jeffrey Carter wrote:
> 
> Kai Gl�sner wrote:
> >
> > This:
> >
> >     Alt_D := (-8.0/4.0) ** 2.0;
> >
> > raises this:
> >
> >     raised ADA.NUMERICS.ARGUMENT_ERROR : a-ngelfu.adb:111 instantiated
> > at a-nuelfu.ads:20
> >
> > This:
> >
> >     Alt_D := -2.0 ** 2.0;
> >
> > works fine!
> 
> Exponentiation has higher precedence than unary minus (ARM 4.5), so this
> is equivalent to
> 
> Alt_D := -(2.0 ** 2.0);
> 
> ARM A.5.1 says that Argument_Error is raised "by the exponentiation
> operator, when the value of the left operand is negative". This is the
> case in your first example.
> 
> Since your exponent is an integer value, you can avoid this restriction
> by using the predefined exponentiation operator for floating-point
> types:
> 
> Alt_D := (-8.0 / 4.0) ** 2;
> 
> --
> Jeff Carter
> "Your mother was a hamster and your father smelt of elderberries."
> Monty Python & the Holy Grail