On Friday, February 29, 2008 at 10:46:02 (+0000) Andrew Ross writes:
> ...
> The reason (not an excuse!) that these functions are not documented is
> that they are not part of our common API. They are only used in the C
> examples and are provided as a convenience. Plplot just uses standard C
> 2-d arrays. You can allocate and free these yourself using malloc /
> free if you like. Of course other languages have their own way of
> allocating arrays and so don't need these functions for the other
> bindings.
A caveat: these are not quite the same thing as "standard C 2-d arrays",
that is if you mean the result of:
PLFLT f[nx][ny];
These are a poor substitute for a real type, which should either know its
dimensions or at least be addressable without carrying extra baggage along.
So instead of an array of pointers to PLFLT, this is an array of an array of
pointers to PLFLT (right about now the Fortran folks are probably shuddering).
While convenient, it's also a lousy data storage layout for high-speed trips
through an inner loop due to stride issues. No problem -- store the data
however you want in your code for maximum efficiency, and then copy it to one
of these plAlloc2dGrid style arrays when getting ready to plot. Or use one of
the function evaluator approaches to lookup your data in its native format.
* plAlloc2dGrid()
*
* Allocates a block of memory for use as a 2-d grid of PLFLT's.
* Resulting array can be indexed as f[i][j] anywhere. This is to be used
* instead of PLFLT f[nx][ny], which is less useful. Note that this type
* of allocation is required by the PLplot functions which take a 2-d
* grids of PLFLT's as an argument, such as plcont() and plot3d().
* Example usage:
*
* PLFLT **z;
*
* Alloc2dGrid(&z, XPTS, YPTS);
> Having said that, we should document them. Thanks for pointing this out.
>
> Andrew
--
Maurice LeBrun
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