Ferret Version 5.3 and Version 5.4  Release Notes

Combined release notes for Versions 5.33 and 5.4

This document includes:

New in Version 5.3

New in Version 5.4

Bug Fixes in Version 5.3

Bug Fixes in Version 5.4

Improved error messages

New Features and Enhancements in Version 5.3

Alpha-level support for string variables

NOTE: See significant additions to capabilities in V5.4

Support for non-Gregorian calendar axes

The NetCDF conventions document discusses and defines usage for different calendar axes.  See:

The NetCDF conventions recommend that the calendar be specified by the attribute calendar which is assigned to the time coordinate variable. These conventions for calendars are implemented in Ferret version 5.3  The calendars defined are: Gregorian (the default), noleap (365 day years), Julian (every four years is leap year), 360day (years are 360 days divided into 30-day months).  These calendars are compatible with the Udunits standard which has slightly different naming conventions.
NetCDF files use the attribute time:calendar when there is a non-Gregorian calendar associated with a data set, i.e.

Example: Define a calendar axis, regrid an existing variable to this axis:
yes? DEFINE AXIS/CALENDAR=360DAY/T="15-JAN-1982":"15-DEC-1985":30/UNITS=days  tmodel
yes? LET twind = uwnd[GT=tmodel@NRST]

When regridding from one calendar axis to another the length of a year is assumed to be constant, therefore the regridding calculates a scale factor based on the length of a second in each calendar, computed from the number of seconds per year for the calendars.

Output from Unix shell commands may be captured in Ferret

As with this example.

     yes? let a = {system:"ls"}
     yes? list a
      1   / 1:"TutorialModels98.zip"
      2   / 2:"ferret.jnl"
      3   / 3:"movies.zip"
      4   / 4:"movies1.zip"
      5   / 5:"movies2.zip"
      6   / 6:"movies3.zip"
      7   / 7:"roseent8054c_timelocked2.exe"
      8   / 8:"tutorial.zip"

New automatically defined symbols for date and time

New pseudo-variables reveal grid cell bounds

XBOXLO, XBOXHI, YBOXLO, ... reveal the grid cell lower and upper bounds explicitly

SHOW AXIS (and SHOW GRID/[axis]) enhanced

enhanced to show lower bound of each grid cell
SHOW GRID, SET GRID, DEFINE GRID/LIKE= and SET VAR/GRID=    can take expressions as arguments

Immediate mode (grave accent) expressions formatting

These may be formatted with w=width or zw=zero-filled width. For example

yes? SAY Answer: `5.3,w=8`
Answer:      5.3
yes? SAY Answer: `5.3,zw=8`
Answer: 000005.3

Nearest coordinate regridding transformation @NRST

Nearest coordinate regridding VAR[GX=newaxis@NRST] chooses the value from the source axis coordinate closest to the destination axis. If source coordinates above and below are equally close to a destination coordinate the value at the  lower coordinate will be chosen. (This is most useful for regridding between axes whose coordinate values are very close, though not exactly matched -- e.g. between equally and unequally spaced monthly time axes.)

Ferret symbols (e.g. "($symbol)") that are used inside of REPEAT loops are now re-translated at each repetition of the loop

Multi-line commands (continuation lines)

Command lines ending with back slash are regarded as incomplete -- a special prompt is given to indicate that the next line is a continuation .

yes? let a = 123 + 456 + \
...? 789
yes? list a
            123 + 456 + 789

The length of the command buffer is increased to 2048 characters

New immediate mode RETURN arguments

Up to 99 arguments for Go commands using either $nn or ($nn) syntax

New transformation @EVNT ("event mask").


This is effectively a RENAME command -- applies to all classes of variables (not pseudo-variables). Useful for "repairing" variables whose definitions are inadequate as-is but whose variable names are significant. A common application of this is in creating output NetCDF files in which contain modified versions of variables from input files.
NetCDF time axes encoded as year 0000 or 0001 are automatically flagged as modulo

Ability to animate on the fly

is used to start an animation sequence. Given LOOP=n, the animation sequence will repeat n times.

    yes? set data coads_climatology
    yes? repeat/l=1:12/animate/loop=5 (shade sst; go fland)

NOTE: In order to properly display on SGI's, it is necessary to have backing store enabled for the Xserver.

FLOWLINE command draws "flowlines" from vector components

(in beta versions this was named STREAKLINE).  A new qualifier to the VECTOR command VECTOR/FLOWLINE (alias FLOWLINE) draws continuous flowlines from the vector components U and V.   The qualifier /DENSITY controls the number of lines drawn.  There is also a 4-argument form of this command for drawing flowlines in curvilinear coordinates. Note that Ferret does not compute a stream function, but draws a pathline integration of a 2-dimensional instantaneous flow field.   In a 3-dimensional flow field the plots are only useful as a qualitative visualization tool.

yes? USE coads_climatology
yes? SET REGION/x=150e:130w/y=40s:50n/l=6
yes? FLOW/DENSITY=4 uwnd,vwnd

The underlying algorithm is used with permission from the GrADS program. Our thanks to COLA, the Center for Ocean-Land-Atmosphere Studies, for access to this technique.

Step function plots

PLOT/STEP and PLOT/STEP=connected
These qualifiers give a plot style that is consistent with grid cell interpretation of data. Especially useful for time series to show the span of each time bin.

New PLOT qualifiers /VLOG and /HLOG set log axes for 1-D plots.

Ability to read "delimited" files (e.g. Excel spreadsheet outputs)


initializes a file of mixed numerical, string, and date fields. If the data types are not specified the file will be analyzed automatically to determine data types. Using delimited files, the number of variables that can be read from a single file is increased from 20 to 100.


/DELIMITER - list of field delimiters. Default is tab or comma   e.g. /DELIM="X,\t,\,"
special characters include

  • \b - blank
  • \t - tab
  • \n - newline
  • \nnn - decimal value from ASCII table
  • /TYPE is the list of data types of the fields. Field types may be any of
  • "-" - skipped
  • TEXT
  • LATITUDE - e.g.  87S or 21.5N (interpreted as negative or positive, respectively)
  • LONGITUDE - e.g. 160W or 30E (interpreted as negative or positive, respectively)
  • DATE - e.g. mm/dd/yy or mm/dd/yyyy or yyyy-mm-dd or yyyymmdd - value returned is days from 1-jan-1900 (consistent with the DAYS1900 function)

  • EURODATE - e.g. dd/mm/yy or dd/mm/yyyy or yyyy-mm-dd TIME - e.g. hh:mm or hh:mm:ss.s

    Enhanced ability to associate time series files into a MC (multi-CDF) data set

    Previous to version 5.2 Ferret performs sanity checking on an MC data set by comparing the time coordinates with those found in the data files as the data are read.  In version 5.3 and higher no sanity checks are performed. This means that the MC descriptor mechanism can be used to associate into time series groups of files that are not internally self documenting with respect to time, however, it also shifts an additional burden onto the user of carefully checking the validity of the STEPFILE records in the descriptor files.   Also note there is enhanced documentation of MC descriptors in the Users Guide, Chapter 10 sec 4.

    Length of filenames in descriptor files increased from 60 to 512 characters

    This allows for long file pathnames and DODS filenames in MC datasets.
    Performance of NetCDF "SAVE/APPEND ..." greatly increased for large file output

    Support for command files created by Windows (embedded CR characters)

    Files written by Windows software have embedded carriage return characters.  Journal files with this formatting can now be read by Ferret.

    External functions utility calls may be made during custom axis creation

    These functions are similar to ZAXREPLACE but use other regridding methods to replace a Z axis

    Use weighted averaging to convert between alternative monotonic Z axes.  The weighting is
    done according to the portion  of the source box that lies within the destination grid cell.

    Use unweighted averaging to convert between alternative monotonic Z axes.  The function
    finds the source points within each destination box and averages them.

    Arguments to EOF functions changed.

    The second argument in previous versions has been removed. This argument had the functions scale and return only EOF spatial and time functions up to a given percent variance explained. However this didn't save much computation. The functions now return all the EOF's.

         yes?  SHOW FUNCTION eof_*
             Compute EOF spacial fields from XYT field
             A: Variable in x,y,t; may be fcn of z
             frac_timeser: Use only those time series with this fraction valid data
             EOF statistics from XYT field. j=1:#EOFs, j=2:%variation,j=3:eigenvalues
             A: Variable in x,y,t; may be fcn of z
             frac_timeser: Use only those time series with this fraction valid data
             Compute EOF time functions from XYT field.
             A: Variable in x,y,t; may be fcn of z
             frac_timeser: Use only those time series with this fraction valid data

    New Features and Enhancements in Version 5.4

    Support for string variables

         yes? LET a =  {"s1","s2", ,"s3"}
         yes? LIST a
         yes? SAVE/CLOBBER/FILE=test_string.cdf/HEADING=enhanced a[i=2:4]
         yes? LIST a[i=@shf]

    Support for DODS version 3.2

    The features of DODS 3.2 include
    Strides can be applied across the "branch point" of a modulo variable
    Strides can be applied across the "branch point" of a modulo variable without loss of efficiency for NetCDF data set, as long as the stride is an integer fraction of the modulo length* (the number of points on the axis)
    Nesting of GO files is no longer limited to 10 deep.
    Ferret now supports up to 200 deep, but typically you will limited to fewer by Unix itself.
    EXIT/LOOP       exit from current repeat loop
    EXIT/SCRIPT     exit from current script
    EXIT/PROMPT     exit to Ferret prompt
    EXIT/PROGRAM    exit program completely

    "QUIT" in a command file is an alias for EXIT without a qualifier.  It will exit the current script, or the program if you are at the Ferret prompt.

    New option for defining viewports,  DEFINE VIEW/AXES

    Allows the user precise control over the position of plots in viewports. Here the user's limits are interpreted as the normalized positions of the plot axes rather than of the entire viewport.  For example:
    yes? DEFINE VIEWPORT/AXES/XLIM=0.5:1/YLIM=0:0.5 lrax
    yes? SET VIEW lrax
    yes? PLOT/VS/LINE/I=1:314 i*cos(i/20),i*sin(i/20); pause
    yes? PLOT/VS/LINE/NOYADJUST/I=1:314 i*cos(i/20),i*sin(i/20)
    Doubled the default memory to 6.4 Mwords
    Recall that you can always change the memory at startup with the -memsize option, or during a Ferret session with the SET MEMORY command.
    Plotting is no longer limited by a fixed plot memory buffer.
    Memory for plotting is allocated as needed.  Previously there was a fixed memory buffer used for plotting.

    Control of dashed lines with PLOT/DASH[=dn1,up1,dn2,up2]

    This allows use of all the color and thickness controls available with the PLOT qualifiers and control over the dash characteristics using the arguments as in the PPLUS "LINE" command:  DOWN1, UP1, DOWN2, UP2 in inches.

    plot/dash/i=1:100 sin(i/5)
    plot/over/dash=(0.3,0.1,0.3,0.1)/color=red/thick/i=1:100 sin(i/7)
    plot/over/dash=(0.6,0.2,0.1,0.2)/color=blue/thick=1/i=1:1000 sin(i/9)

    New plot qualifier /AXES[=top,bottom,left,right]
    For all plot commands, turns plotting of individual axes off and on.  This is equivalent to the "PPL AXSET" command.  The syntax is

    PLOT/AXES[=top,bottom,left,right]  where the arguments are 1 to turn the axis on and 0 to turn it off.  For example:

    CONTOUR/AXES=0,1,1,0  sst   ! Plots the bottom and left axes only
    One can still use the "ppl axset" command to turn axes off or on, and that setting will persist from one plot to another in a script. The "ppl axset" setting will be restored after a PLOT/AXES= plot is drawn. For example:
    PPL AXSET 0,0,0,0
    PLOT/i=1:12 1./i                 ! no axes drawn
    PLOT/i=1:100/AXES=1,0,0,1 sin(i) ! top and right axes drawn
    SHADE/i=1:10/j=1:5 i+j           ! no axes drawn


    Makes a dot at each point.  This implements the GKS "dot" polymarker,  which uses the smallest dot that can be represented on the display device (Note the dots may not show up well on all devices).
    New functions COMPRESS*_BY Compress data according to a mask
    COMPRESSI_BY (var, mask), COMPRESSJ_BY (var, mask), COMPRESSK_BY (var, mask), COMPRESSL_BY (var, mask)
    Compress variable "dat" along its I (or J, K, or L) axis using the (multi-dimensional) mask supplied in the second argument.
    For example:

    yes? LET mask = {1,,1,,1} + 0*L[l=101:102] + 0*K[k=10:11]
    yes? LIST mask
                 {1,,1,,1} + 0*L[L=101:102] + 0*K[K=10:11]
                   1      2      3      4      5
                   1      2      3      4      5
     ---- L:101 T:   101
     10   / 10:  1.000   ....  1.000   ....  1.000
     11   / 11:  1.000   ....  1.000   ....  1.000
     ---- L:102 T:   102
     10   / 10:  1.000   ....  1.000   ....  1.000
     11   / 11:  1.000   ....  1.000   ....  1.000

    yes?  LIST compressi_by({11,22,33,44,55},mask)
                   1      2      3      4      5
                   1      2      3      4      5
     ---- L:101 T:   101
     10   / 10:  11.00  33.00  55.00   ....   ....
     11   / 11:  11.00  33.00  55.00   ....   ....
     ---- L:102 T:   102
     10   / 10:  11.00  33.00  55.00   ....   ....
     11   / 11:  11.00  33.00  55.00   ....   ....

    Modified heading output of LIST command
    New lines list the file name and path, and complete information on the subset of the data being listed.  See the next section on LIST/WIDTH for an example.
    New qualifier: LIST/WIDTH=columns
    For multi-column output, controls the width of the listing on the page, for example:

    yes? USE coads_climatology
    yes? LIST/L=1/WIDTH=50/Y=0:4 sst
                 DATA SET : COADS Monthly Climatology (1946-1989)
                 FILENAME : coads_climatology.des
                 FILEPATH : /home/ja9/tmap/fer_dsets/descr/
                 SUBSET   : 180 by 2 points (LONGITUDE-LATITUDE)
                 TIME     : 16-JAN      06:00
          ... listing every  36th point
                  21E    93E   165E   123W    51W
                   1     37     73    109    145
     3N   / 47:   ....  28.30  29.04  25.36  27.49
     1N   / 46:   ....  28.29  29.12  24.82  27.49

    yes? LIST/L=1/WIDTH=80/Y=0:4 sst
                 DATA SET : COADS Monthly Climatology (1946-1989)
                 FILENAME : coads_climatology.des
                 FILEPATH : /home/ja9/tmap/fer_dsets/descr/
                 SUBSET   : 180 by 2 points (LONGITUDE-LATITUDE)
                 TIME     : 16-JAN      06:00
          ... listing every  18th point
                  21E    57E    93E   129E   165E   159W   123W    87W    51W    15W
                   1     19     37     55     73     91    109    127    145    163
     3N   / 47:   ....  27.42  28.30  28.10  29.04  27.30  25.36  27.08  27.49  27.90
     1N   / 46:   ....  27.67  28.29  28.48  29.12  26.62  24.82  25.82  27.49  27.41

    Allow the qualifier /TITLE for DODS or NetCDF datasets
    SET DATA/TITLE  associates a title with a dataset (previously not allowed for these file types.)

    Expanded Users' Guide

    includes the PlotPlus manual and Ferret-specific PPLUS enhancements Guide as appendices. Some cross-references and index entries are included; more will be added. New Ferret Users' Guide

    PPLUS Symbol and Font tables are linked to the Documentation webpage

    PPLUS Character Fonts
    PPLUS Symbol Fonts

    Known bugs in Version 5.4

    Backwards compatibility issues:

    Bug descriptions:

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