Pyabel

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* Correct behavior of relative basis_dir in basex under Python 2 (PR 336).
* Improvements in tools.analytical.SampleImage class: more consistent and
intuitive interface, accurate Abel transform for existing images, additional
sample images with exact Abel transform (PR 339, 352).
* Analytical Abel transform of axially symmetric piecewise polynomials in
spherical coordinates (PR 339).
* Offline HTML and PDF documentation is now available at Read the Docs and can
be built locally (PR 343, 348, 349).
* **Important** changes in the **lin-BASEX** implementation (PR 357):

- It was erroneously producing even-sized images with offset origin. Now the
output is odd-sized and properly centered.
- Output images for radial_step > 1 were scaled down by the same factor. Now
they have the save size as the input.
- The sign of Beta for odd Legendre orders is reversed to be consistent with
PyAbel conventions (zero angle is upwards, towards smaller row indices).

* Transform() with method='linbasex' now always stores the radial, Beta and
projection attributes, so there is no need to pass return_Beta=True
in transform_options (PR 357).

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* New functions in tools.vmi for angular integration and averaging, replacing
angular_integration() and average_radial_intensity(), which had incorrect or
nonintuitive behavior (PR 318, PR 319).
* Avoid unnecessary calculations in transform.Transform() for the
symmetry_axis=(0, 1) case (PR 324).
* New method by Daun et al. and its extensions (PR 326).
* Basis sets are now by default stored in a single system-specific directory,
see get_basis_dir() and set_basis_dir() in abel.transform (PR 327).
**Important!** The current working directory is no longer used by default for
loading basis sets. It is recommended to execute

import abel; print(abel.transform.get_basis_dir(make=True))

and move all existing basis sets to the reported directory.
* Cython optimization flags are changed to make conda packages compatible with
all CPUs and to improve the direct_C method performance (PR 331). Bitwise
reproducibility of direct_C transforms might be affected.

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* Added odd angular orders to tools.vmi.Distributions (PR 266).
* **Important!** Some "center" functions/parameters are renamed to "origin" or
"method"; using old names still works but will print deprecation warnings,
please update your code accordingly. Image origin is now always in the
(row, column) format for consistency within PyAbel and with NumPy/SciPy; this
can break some code, so please check carefully and update it if necessary.
See PR 267.
* Fixed the GUI examples (example_GUI.py and example_simple_GUI.py)
so that they work with the lastest versions of tk (PR 269).
* New method rBasex for velocity-map images, based on pBasex and the work of
Mikhail Ryazanov (PR 270).
* Added "orders", "sinpowers" and "valid" to tools.vmi.Distributions results,
reordered cossin() powers for consistency (PR 270).
* Improved tools.vmi.Distributions performance on Windows (PR 270).
* More corrections to the GUI example: working without the "bases" directory,
loading "from transform", interface enhancements (PR 277).
* Improved documentation (PR 283, PR 288).
* Correctly use quadrants in abel.Transform (PR 287).
* Circularization now uses periodic splines (to avoid discontinuity), with
smoothing determined by the RMS tolerance instead of the nonintuitive
"smooth" parameter (PR 293).
* Corrected and improved tools.center (PR 302).
* Moved numpy import to try block in setup.py. This allows pip to install
PyAbel in situations where numpy is not already installed (PR 310).

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* New tools.vmi.Distributions class for extracting radial intensity and
anisotropy distributions (PR 257).
* Dropped PyAbel version from basex cache files (PR 260).

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* Added forward transform to basex method (PR 240).
* Corrected tools.transform_pairs.profile4 (PR 241).
* Removed tools.transform_pairs.profile8, which was the same as profile6
(PR 241).
* Major changes in benchmark.AbelTiming class (PR 244, 252).
* Corrected image shift in onion_bordas method (PR 248).
* Changed gradient calculations in hansenlaw method to first-order finite
difference (PR 249).
* Corrected background width for Dribinski sample image in
tools.analytical.SampleImage (PR 255).

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* Implemented Tikhonov regularization in basex method (PR 227).
* Improvements and changes in basis caching for methods using basis sets
(PR 227, 232, 235).
* Improvements in basis generation for basex method, allow any sigma (PR 235).
* Added intensity correction to basex method (PR 235).
* New tools.polynomial module for analytical Abel transform of piecewise
polynomials (PR 235).


(2016-04-20)
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* Lin-BASEX method of Thomas Gerber and co-workers available (PR 177)

(2016-03-20)
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* Dasch two-point, three-point (updated), and onion-peeling available
(PR 155).

(2016-03-15)
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* Changed abel.transform to be a class rather than a function. The previous
syntax of abel.transform(IM)['transform'] has been replaced with
abel.Transform(IM).transform.