Re: Question

[John Lamb <J.D.Lamb@btinternet.com>]

Przemyslaw Sliwa wrote:
> All,
> 
> I was just wondering what means
> 
> double gsl_cdf_ugaussian_Pinv (const double P)
> 
> Correct me if I am wrong but it seems the const word is not required
> in this case and we cannot change the value of P.
> 

I think you are right, const is not required and you don't need to worry 
about it when calling the function. This is certainly true in C++.

Nonetheless, it is often a good idea to declare an automatic function 
parameter const in the function definition. This forces the compiler to 
check that you don't change the parameter value in the body of the 
function. Similarly, it is a good idea to declare any variable const if 
you don't intend to change it.

You can declare the function as

double gsl_cdf_ugaussian_Pinv (double);

and define it as

double gsl_cdf_ugaussian_Pinv (const double P){
...
}

but it may be better to make the two match precisely either because you 
may want to use some editing tools that rely on a match or because you 
want the code to work on a compiler that can't work oout that the 
declaration and definition do match.

-- 
JDL