Legendre polynomial documentation

Legendre polynomial documentation

[M Joonas Pihlaja]

Hi,

The reference manual's entries for the array versions of the 
associated Legendre polynomials and spherical harmonics are a 
little confusing I think.

1) The _array function documentation uses the absolute value |m| 
as the lower bound of the array indices yet also specifies m
>= 0.  Why the absolute value if negative m aren't allowed after
all?

2) The docs say the _deriv_array functions compute "optionally 
their derivatives", which made me think that the 
result_deriv_array parameter could be passed in as NULL if one 
didn't need the derivatives.  Turns out that's not what it meant. 
:)  The phrasing could be a little bit more explicit IMHO.

Cheers,

Joonas

Re: Legendre polynomial documentation

[Brian Gough]

At Mon, 9 Feb 2009 07:38:21 +0200 (EET),
M Joonas Pihlaja wrote:
> 1) The _array function documentation uses the absolute value |m| 
> as the lower bound of the array indices yet also specifies m
> >= 0.  Why the absolute value if negative m aren't allowed after
> all?

Although it's not implemented, I expect there was an intention to
extend the function to include negative m at some point.

> 2) The docs say the _deriv_array functions compute "optionally 
> their derivatives", which made me think that the 
> result_deriv_array parameter could be passed in as NULL if one 
> didn't need the derivatives.  Turns out that's not what it meant. 
> :)  The phrasing could be a little bit more explicit IMHO.

Ok, I've changed the wording to avoid the confusion.

-- 
Brian Gough