ambiguous universal_fixed_expression

ambiguous universal_fixed_expression

[xadian]

Hi

I've got a problem with an Ada program(surprise ;D).
With this line:

x := sol_Ty((var_Ar(f)*var_Ar(b))-(var_Ar(e)*var_Ar(c))/z);
-- x : sol_Ty := (f*b - e*c) / z;

I get the following errors:
 > ambiguous universal_fixed_expression
 > possible interpretation as type "Standard.duration"
 > possible interpretation as type "sol_Ty" defined at line 8
The minus in the middle is highlighted after the errors.

var_Ar is an array of the type sol_Ty and x is also sol_Ty. sol_Ty 
definition is a decimal fixed point:
 > type sol_Ty   is delta 0.01 digits 18;
I never worked with duration so can anyone tell me (or link something) 
what it is and why it can be missinterpreted in this case? And how i can 
GENERALLY solve it?!

thx already
xadian

Re: ambiguous universal_fixed_expression

[Martin Krischik]

xadian wrote:

> Hi
> 
> I've got a problem with an Ada program(surprise ;D).
> With this line:
> 
> x := sol_Ty((var_Ar(f)*var_Ar(b))-(var_Ar(e)*var_Ar(c))/z);
> -- x : sol_Ty := (f*b - e*c) / z;
> 
> I get the following errors:
>  > ambiguous universal_fixed_expression
>  > possible interpretation as type "Standard.duration"
>  > possible interpretation as type "sol_Ty" defined at line 8
> The minus in the middle is highlighted after the errors.

> var_Ar is an array of the type sol_Ty and x is also sol_Ty. sol_Ty
> definition is a decimal fixed point:
>  > type sol_Ty   is delta 0.01 digits 18;
> I never worked with duration so can anyone tell me (or link something)
> what it is and why it can be missinterpreted in this case? And how i can
> GENERALLY solve it?!

Maybe you should try sol_Ty'( instead of sol_Ty(. The difference is subtle:
the first means "interpret as" the other "convert to". the ' notiation is
paricular usefull for contants like 1.0 or so.

With Regards

Martin

-- 
mailto://krischik@users.sourceforge.net
http://www.ada.krischik.com

Re: ambiguous universal_fixed_expression

[Jeffrey Carter]

xadian wrote:

> x := sol_Ty((var_Ar(f)*var_Ar(b))-(var_Ar(e)*var_Ar(c))/z);
> -- x : sol_Ty := (f*b - e*c) / z;
> 
> I get the following errors:
>  > ambiguous universal_fixed_expression
>  > possible interpretation as type "Standard.duration"
>  > possible interpretation as type "sol_Ty" defined at line 8
> The minus in the middle is highlighted after the errors.

Multiplication and division of fixed-point values results in a value of 
Universal_Fixed (ARM 4.5.5). Addition and subtraction, on the other 
hand, take arguments of a specific fixed-point type and return a value 
of the same type. So you need to tell the compiler the type of the 
results of the multiplications:

X := Sol_Ty (Sol_Ty'(Var_Ar (F) * Var_Ar (B) ) -
              Sol_Ty'(Var_Ar (E) * Var_Ar (C) ) / Z);

-- 
Jeff Carter
"Many times we're given rhymes that are quite unsingable."
Monty Python and the Holy Grail
57