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Changes that were made in July 2006 by Joshua Reich I.
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Code Cleanup:

Update the calling convention for all external facing functions. By external
facing, I mean all functions that are directly referenced in cube.sql. Prior
to my update, all functions used the older V0 calling convention. They now 
use V1.

New Functions: 

cube(float[]), which makes a zero volume cube from a float array

cube(float[], float[]), which allows the user to create a cube from
two float arrays; one for the upper right and one for the lower left
coordinate.

cube_subset(cube, int4[]), to allow you to reorder or choose a subset of
dimensions from a cube, using index values specified in the array.

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Changes that were made in August/September 2002 by Bruno Wolff III.
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Note that this was based on a 7.3 development version and changes may not
directly work with earlier versions.

I fixed a bug in cubescan.pl that prevented signed numbers with no digits
before a decimal point from being accepted. This was submitted as a separate
patch and may already be applied.

cube_inter should really return NULL if the two cubes don't overlap. However
this requires changing to the new calling sequence and I don't know enough
about how to do it to make the change.

I changed all floats to doubles except for g_cube_penalty which I don't
think can be changed to return double. This might cause the penalty to
overflow sooner than one might expect, but overflow could have happened
even with floats.

I changed the output format (in cube_out) to use %.16g instead of %g, since the
default is only 6 digits of precision.

I changed all of the functions declared with (isstrict) to use the current
method of declaring this.

I changed all of the externally visible functions to be immutable which
they are. I don't think this matters for the gist functions and didn't
try to declare them immutable in case there was something tricky about them
that I don't understand.

I changed the regression tests to use some larger exponents to test output
in exponential form. 1e7 was too small for this.

I added some regression tests to check for 16 digits of precision. This
may or may not be a good idea.

I got rid of the swap_corners function. It created scratch boxes that
were iterated through and deleted. This is slower than just getting the
larger or smaller coordinate as needed, since swap_corners was doing the
same thing with the overhead of a function call and memory allocation.

I added memset calls to zero out newly allocated NDBOXes as the documentation
on functions indicates should be done. This still doesn't allow a hash
index for equality since there are multiple representations of the
same cube.

I got rid of a call to cube_same in cube_lt and cube_gt since the test
was redundant with other checks being made. The call to cube_same would
only be faster if most of the time you were comparing equivalent cubes.

In cube_lt and cube_gt, the second (UR) for loop for comparing
extra coordinates to 0 had the wrong range.

Note that the cube_distance function wasn't mentioned in the README.cube file.

I added regression tests for the cube_distance function.

I added the following new functions:
cube
cube_dim
cube_ll_coord
cube_ur_coord
cube_is_point
cube_enlarge

cube takes text input and returns a cube. This is useful for making cubes
from computed strings.

cube_dim returns the number of dimensions stored in the data structure
for a cube. This is useful for constraints on the dimensions of a cube.

cube_ll_coord returns the nth coordinate value for the lower left corner
of a cube. This is useful for doing coordinate transformations.

cube_ur_coord returns the nth coordinate value for the upper right corner
of a cube. This is useful for doing coordinate transformations.

cube_is_point returns true if a cube is also a point. This is true when the
two defining corners are the same.

cube_enlarge increases the size of a cube by a specified radius in at least
n dimensions. If the radius is negative the box is shrunk instead. This
is useful for creating bounding boxes around a point for searching for
nearby points. All defined dimensions are changed by the radius. If n
is greater than the number of defined dimensions and the cube is being
increased (r >= 0) then 0 is used as the base for the extra coordinates.
LL coordinates are decreased by r and UR coordinates are increased by r. If a
LL coordinate is increased to larger than the corresponding UR coordinate
(this can only happen when r < 0) than both coordinates are set to their
average.

I added regression tests for the new functions.

I added documentation for cube_distance and the new functions to README.cube
as well as making a few other minor changes.

I changed create function to create or replace function in the install
script.

I limited the number of dimensions allowed in cube_enlarge and cube_in
to 100 to make it harder for people to mess up the database. The constant
is defined in cubedata.h and can be increased if you need something larger.

I added grant statements to the install script to make the functions
executable to everyone.

Bruno Wolff III <bruno@wolff.to>
