Re: increment a single element of matrix/vector

[Patrick Alken <patrick.alken@Colorado.EDU>]

On 01/28/2014 02:16 PM, Rhys Ulerich wrote:
>>>>> *gsl_vector_ptr(v, i) += x
>>> *(gsl_vector_ptr(v, i)) += x;
> Why the extra parens?  They hurt nothing, but the former statement
> without them works just fine for me.  Unless I'm mistaken, the
> function application happens before the dereference.  And the
> dereference is much, much higher than anything like += or *= that the
> user might want.

Yes sorry I didn't see the * the first time I read that
>>> This could lead to trouble so its probably better to have a function
>>> which does range checking, etc.
> There is range checking in gsl_vector_ptr, so long as someone doesn't
> start doing pointer arithmetic on its result.
>
> Lastly, the pointer-based solution is nicely general: *(i > j ?
> gsl_vector_ptr(v, i) : gsl_vector_ptr(j)) += 1
>
> - Rhys

Hmm ok you convinced me, I'll reverse those last few commits