Summary of important user-visible changes for version 5 (2019-02-23):
--------------------------------------------------------------------

### General improvements

- The Octave plotting system now supports high resolution screens,
  i.e., those with greater than 96 DPI which are referred to as
  HiDPI/Retina monitors.

- Unicode character support for files and folders in Windows.

- A new core function `movfun` will apply a function to a sliding
  window of arbitrary size on a dataset and accumulate the results.
  Many common cases have been implemented using the naming
  scheme `movXXX` where `XXX` is the function that will be applied.
  For example, the moving average over a dataset is `movmean`.
  New moving window functions:

  `movfun`  `movslice`
  `movmad`  `movmax`   `movmean`  `movmedian`  `movmin`  `movprod`
  `movstd`  `movsum`   `movvar`

- The `fsolve` function has been tweaked to use larger step sizes when
  calculating the Jacobian of a function with finite differences.
  This leads to faster convergence.

- The `ranks` function has been recoded for performance and is now 25X
  faster.  In addition, it now supports a third argument that specifies
  how to resolve the ranking of tie values.

- The function `randi` has been recoded to produce an unbiased (all
  results are equally likely) sample of integers.  This may produce
  different results in existing code.  If it is necessary to reproduce
  the exact random integer sequence as in previous versions use

  `ri = imin + floor ((imax - imin + 1) * rand ());`

- The function `isdefinite` now returns `true` or `false` rather than
  `-1`, `0`, or `1`.  To test for a positive semi-definite matrix (old
  output of `0`) check whether the following two conditions hold:

    `isdefinite (A) => 0`  and  `isdefinite (A + 5*TOL, TOL) => 1`

- The `intmax`, `intmin`, and `flintmax` functions now accept a variable
  as input.  Existing code to query the range of an existing variable can
  be simplified by removing the call to `class` that was previously
  required.  For example defining the variable `x = int8 (3)` in the
  workspace, calls like

    `range = [ intmin(class(x)), intmax(class(x)) ]`

  can in Octave 5 be simplified to `range = [ intmin(x), intmax(x) ]`.

- The path handling functions no longer perform variable or brace
  expansion on path elements and Octave's load-path is no longer
  subject to these expansions.

- A new printing device is available, `"-ddumb"`, which produces ASCII
  art for plots.  This device is only available with the gnuplot toolkit.

- The `msgbox` function has changed in two respects: the default WindowStyle
  is now `"non-modal"`, and the default interpreter for the message is now
  `"tex"`.  Both WindowStyle and Interpreter can be controlled by passing an
  option struct argument.

### Dependencies

- The GUI requires Qt libraries.  The minimum Qt4 version supported is
  Qt4.8.  Qt5 of any version is preferred.

- The OSMesa library is no longer used.  To print invisible figures
  when using OpenGL graphics, the Qt `QOFFSCREENSURFACE` feature must be
  available and you must use the qt graphics toolkit.

- The FFTW library is now required to perform FFT calculations.
  The FFTPACK sources have been removed from Octave.


### Matlab compatibility

- The determination of an object's dimensions, size, and shape by the
  functions `ndims`, `rows`, `columns`, `isscalar`, `isvector`,
  `isrow`, `iscolumn`, `ismatrix`, and `issquare` now fully depends
  on the function size.  Thus, any user-defined object can ensure correct
  treatment by the aforementioned functions by properly overloading the
  `size` function.

- The functions `issymmetric` and `ishermitian` accept an option
  `"nonskew"` or `"skew"` to calculate the symmetric or skew-symmetric
  property of a matrix.  Performance has also been increased.

- The `issorted` function now uses a direction option of `"ascend"`
  or `"descend"`.  Change all uses of `"ascending"` and `"descending"`
  in existing code to the new options.

- The `strncmp` and `strncmpi` functions now return `true` if the two
  input strings match, even though the number of characters specified
  by `n` exceeds the string length.  For Example:

    `strncmp ("abc", "abc", 100)`

  returns `true` in Octave 5 and `false` in older versions of Octave.

- The `str2func` function no longer accepts a second `"global"` argument.
  This argument was typically used to allow functions that accept
  function names as arguments to avoid conflicts with subfunctions or
  nested functions.  Instead, it's best to avoid this situation
  entirely and require users to pass function handles rather than
  function names.

- Using `clear` with no arguments now removes only local variables
  from the current workspace.  Global variables will no longer be
  visible, but they continue to exist in the global workspace and
  possibly other workspaces such as the base workspace.


#### Nonlinear Equations

Several default solver options have been changed to be Matlab compatible.
This *may* result in existing code producing different results.

- `fsolve`

  Option         |   New Default    | Old Default
  ---------------|------------------|-------------
  `FinDiffType`  |    `"forward"`   |  `"central"`
  `MaxFunEvals`  | `100*length(x0)` |    `Inf`
  `TolFun`       |     `1e-6`       |    `1e-7`
  `TolX`         |     `1e-6`       |    `1e-7`
  `Updating`     |     `"off"`      |    `"on"`

- `fminsearch`

  Option   | New Default | Old Default
  ---------|-------------|------------
  `TolFun` |   `1e-7`    |   `1e-4`

- `fminbnd`

  Option         | New Default | Old Default
  ---------------|-------------|------------
  `MaxFunEvals`  |     `500`   |   `Inf`
  `MaxIter`      |     `500`   |   `Inf`
  `TolX`         |    `1e-4`   |   `1e-8`

- `fminunc`

  Option         |   New Default    | Old Default
  ---------------|------------------|------------
  `FinDiffType`  |   `"forward"`    | `"central"`
  `MaxFunEvals`  | `100*length(x0)` |   `Inf`
  `TolX`         |     `1e-6`       |   `1e-7`
  `TolFun`       |     `1e-6`       |   `1e-7`


#### Graphic objects

- Figure graphic objects have a new property `"Number"` which is
  read-only and will return the handle (number) of the figure.
  However, if the property `"IntegerHandle"` has been set to `"off"`
  then the property will return an empty matrix `[]`.

- Patch and surface graphic objects now use the `"FaceNormals"` property
  for flat lighting.

- `"FaceNormals"` and `"VertexNormals"` for patch and surface graphic
  objects are now calculated only when necessary to improve graphics
  performance.  In order for any normals to be calculated the
  `"FaceLighting"` property must be set to `"flat"` (FaceNormals) or
  `"gouraud"` (VertexNormals), **and** a light object must be present
  in the axes.

- The `"Margin"` property of `text`-objects has a new default of `3`
  rather than `2`.

- Printing to raster formats (bitmaps like PNG or JPEG) now uses an
  OpenGL-based method by default.  The print options `"-opengl"`
  (raster) and `"-painters"` (vector) have been added ("qt" toolkit
  only).  The figure property `"renderer"` specifies which renderer to
  use.  When the property `"renderermode"` is `"auto"` Octave will select
  `"-opengl"` for a raster output format and `"-painters"` for a vector
  output format.

- A new print option `"-RGBImage"` has been added which captures the
  pixels of a figure as an image.  This is similar to screen capture
  tools, except that print formatting options can be used to, for
  example, change the resolution or display the image in black and
  white.

- Two new print options for page-based formats (PDF, PostScript) have
  been added.  The `"-fillpage"` option will stretch the plot to occupy
  the entire page with 0.25 inch margins all around.  The `"-bestfit"`
  option will expand the plot to take up as much room as possible on
  the page without distorting the original aspect ratio of the plot.

- Printing using the `"-dtiff"` output device will now create compressed
  images using LZW compression.  To produce uncompressed images use the
  `"-dtiffn"` device.


### Legacy functions

The following functions have been declared legacy functions which
means they are obsolete and should not be used in any new code.
Unlike deprecated functions, however, their removal from Octave has
not yet been scheduled.

  Function               | Replacement
  -----------------------|------------------
  `findstr`              | `strfind`
  `flipdim`              | `flip`
  `isdir`                | `isfolder` or `dir_in_loadpath`
  `isequalwithequalnans` | `isequaln`
  `isstr`                | `ischar`
  `setstr`               | `char`
  `strmatch`             | `strncmp` or `strcmp`
  `strread`              | `textscan`
  `textread`             | `textscan`


### Deprecated functions and properties

The following functions and graphics properties have been deprecated
in Octave 5 and will be removed from Octave 7 (or whatever version
is the second major release after 5):

- Functions

  Function                 | Replacement
  -------------------------|-------------------
  `output_max_field_width` | `output_precision`
  `is_keyword`             | `iskeyword`

- Graphics properties

  Object           | Property      | Value
  -----------------|---------------|------------
  `text`           | `fontangle`   | `"oblique"`
  `uibuttongroup`  | `fontangle`   | `"oblique"`
  `uicontrol`      | `fontangle`   | `"oblique"`
  `uipanel`        | `fontangle`   | `"oblique"`
  `uitable`        | `fontangle`   | `"oblique"`

- Specifying `legend` position with a numeric argument is deprecated.
  Use a string argument instead.

- The environment variable used by `mkoctfile` for linker flags is now
  `LDFLAGS` rather than `LFLAGS`.  `LFLAGS` is deprecated, and a warning
  is emitted if is used, but it will continue to work.


### Removed functions and properties

The following functions and properties were deprecated in Octave 4.2
and have been removed from Octave 5.

- Functions

  Function               | Replacement
  -----------------------|------------------
  `bitmax`               | `flintmax`
  `mahalanobis`          | `mahal` in Octave Forge statistics pkg
  `md5sum`               | `hash`
  `octave_config_info`   | `__octave_config_info__`
  `onenormest`           | `normest1`
  `sleep`                | `pause`
  `usleep`               | `pause`
  `wavread`              | `audioread`
  `wavwrite`             | `audiowrite`

- Properties

  Object      | Property          | Value
  ------------|-------------------|---------
  `axes`      | `xaxislocation`   | `"zero"`
              | `yaxislocation`   | `"zero"`
  `hggroup`   | `erasemode`       |
  `image`     | `erasemode`       |
  `line`      | `erasemode`       |
  `patch`     | `erasemode`       |
  `patch`     | `normalmode`      |
  `surface`   | `erasemode`       |
  `surface`   | `normalmode`      |
  `text`      | `erasemode`       |


### Alphabetical list of new functions added in 5

- `clearvars`
- `isfile`
- `isfolder`
- `matlab.lang.makeUniqueStrings`
- `matlab.lang.makeValidName`
- `movegui`
- `movfun`
- `movie`
- `movmad`
- `movmax`
- `movmean`
- `movmedian`
- `movmin`
- `movprod`
- `movslice`
- `movstd`
- `movsum`
- `movvar`
- `openfig`
- `ordeig`
- `savefig`
- `uitable`


### Old release news

- [Octave 4.4.x](etc/NEWS.4)
- [Octave 4.2.x](etc/NEWS.4)
- [Octave 4.0.x](etc/NEWS.4)
- [Octave 3.8.x](etc/NEWS.3)
- [Octave 3.6.x](etc/NEWS.3)
- [Octave 3.4.x](etc/NEWS.3)
- [Octave 3.2.x](etc/NEWS.3)
- [Octave 3.0.x](etc/NEWS.3)
- [Octave 2.x](etc/NEWS.2)
- [Octave 1.x](etc/NEWS.1)
