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6.9 SPECIAL SYMBOLS

by rohan — last modified 2011-04-05 10:49

When Ferret starts, several global symbols are set which describe the Ferret version, the date and time when the Ferret session started, and the amount of memory Ferret has allocated.  Some of these remain fixed for the Ferret session, and others will be updated later in the Ferret session to reflect the current state of things.

When a plot command is executed, PPLUS automatically defines a number of global symbols which are available to the user with SHOW SYMBOL They are listed here, and also documented in the PPLUS Users Guide. These are not defined until associated plot commands have been issued. Also note that the user cannot redefine the value of these symbols.

Example: draw a plot and examine and use some of the symbols

yes? plot/i=1:10 1./i
yes? SHOW SYMBOL ppl$xlen
PPL$XLEN = "8.000"

! Try to show an undefined variable (no response)
yes? SHOW SYMBOL ppl$lf_var

yes? SHOW SYMBOL ppl$line_count
PPL$LINE_COUNT = " 1"

! Use the value of a symbol to position a label
yes? LET my_xlen = ($ppl$xlen) - 1.
DEFINE VARIABLE my_xlen = 8.00 - 1.

yes? LABEL/NOUSER `my_xlen`, 0.1, -1, 0, 0.1 "label at `my_xlen`"




SYMBOL PPL COMMAND DESCRIPTION

PPL$EOF

RD,RWD,SKP

"YES" if an EOF (end of file) was read.

PPL$FORMAT

FORMAT

The current format.

PPL$HEIGHT

SIZE

Height of the box.

PPL$INPUT_FILE

RD,SKP,RWD

The current input file.

PPL$LF_A

LINFIT

Constant from fit y= a + b*x

PPL$LF_A_STDEV

LINFIT

Standard error of A.

PPL$LF_B

LINFIT

Constant from fit.

PPL$LF_B_STDEV

LINFIT

Standard error of B.

PPL$LF_R2

LINFIT

Regression coefficient squared.

PPL$LF_RES_VAR

LINFIT

Residual variance.

PPL$LF_VAR

LINFIT

Total variance.

PPL$LINE_COUNT

-

The number of the last line read.

PPL$PLTNME

PLTNME

The name of the plot file.

PPL$RANGE_INC

%RANGE

see %RANGE

PPL$RANGE_HIGH

%RANGE

see %RANGE

PPL$RANGE_LOW

%RANGE

see %RANGE

PPL$TEKNME

TEKNME

The name of the tektronix file.

PPL$VIEW_X

VPOINT

X viewpoint (from a WIRE plot)

PPL$VIEW_Y

VPOINT

Y viewpoint (from a WIRE plot)t

PPL$VIEW_Z

VPOINT

Z viewpoint (from a WIRE plot)

PPL$WIDTH

SIZE

Width of the box.

PPL$XFACT(n)

TRANSXY

Xfact for line n.

PPL$XLEN

AXLEN

Length of X axis.

PPL$XOFF(n)

TRANSXY

Xoff for line n.

PPL$XORG

ORIGIN

Distance between origin and left edge.

PPL$XFIRST(n)

-

X value for first data point in line n.

PPL$XLAST(n)

-

X value for last data point in line n.

PPL$XMAX

RD

Xmax of contour grid

PPL$XMIN

RD

Xmin of contour grid

PPL$XMAX(n)

-

Xmax for valid data in line n.

PPL$XMIN(n)

-

Xmin for valid data in line n.

PPL$YFACT(n)

TRANSXY

Yfact for line n.

PPL$YLEN

AXLEN

Length of Y axis.

PPL$YOFF(n)

TRANSXY

Yoff for line n.

PPL$YORG

ORIGIN

Distance between origin and bottom edge.

PPL$YFIRST(n)

-

Y value for first data point in ine n.

PPL$YLAST(n)

-

Y value for last data point in line n.

PPL$YMAX

RD

Ymax of contour grid

PPL$YMIN

RD

Ymin of contour grid

PPL$YMAX(n)

-

Ymax for valid data in line n.

PPL$YMIN(n)

-

Ymin for valid data in line n.

PPL$ZMAX

-

Zmax for valid contour data.

PPL$ZMIN

-

Zmin for valid contour data.



In addition to the PPLUS symbols, Ferret sets other symbols on startup or when plotting commands are issued. They are summarized here.

SYMBOL FERRET COMMAND DESCRIPTION

FERRET_VERSION

set at startup

the Ferret version

FERRET_PLATFORM

set at startup

the platform Ferret is running on

 FERRET_MEMORY set at startup,
reset on SET MEMORY/SIZ
 the current memory setting, in Mwords

BYTEORDER

set at startup

gives "BIG" or "LITTLE" according to the endianness of the CPU

SESSION_DATE

set at startup

date the current Ferret session started

SESSION_TIME

set at startup

time the current Ferret session started

CURRENT_DATE
set when symbol is evaluated
date the symbol is evaluated, e.g. 14-May-09 (available in Ferret v6.2)
CURRENT_TIME set when symbol is evaluated date the symbol is evaluated, e.g. 15:07:29
(available in Ferret v6.2)
DELTA_CPU initialized at startup, updated when symbol is evaluated
cpu time in seconds used by the Ferret process, since the last time this symbol was evaluated.
(available in Ferret v6.2)
CLOCK_SECS initialized at startup, updated when symbol is evaluated elapsed time in seconds since the Ferret process began. (available in Ferret v6.2)

LABTIT

plot commands

default title label; if title is set with /TITLE or PPL TITLE, this new title is stored in a movable label

LABX

plot commands

label for horizontal axis

LABY

plot commands

label for vertical axis

LABn

plot commands

nth moveable label

LABNUM_X

plot commands

label number for X location at upper left, when X axis is normal to the plot

LABNUM_Y

plot commands

label number for Y location a upper left, when Y axis is normal to the plot

LABNUM_Z

plot commands

label number for Z location at upper left, when Z axis is normal to the plot

LABNUM_T

plot commands

label number for T location at upper left, when T axis is normal to the plot

LABNUM_DSET

plot commands

label number for the dataset label at upper right

LABNUM_CALEND

plot commands

label number for non-standard calendar time axes, at the upper left

LABNUM_YEAR

plot commands

label number, year label at upper left, on month or day time series plots

LABNUM_DATITL

plot commands

label number, dataset title at upper right

LABNUM_DODS

plot commands

label number, dataset URL at upper right

LABNUM_ASPECT

plot commands

label number, label for VECTOR/ASPECT at upper left

LABNUM_OFFSET

plot commands

label number, label for staggered vectors at upper left

XAXIS_MIN

plot commands

data value corresponding to the start of the horizontal axis

XAXIS_MAX

plot commands

data value corresponding to the end of the horizontal axis

YAXIS_MIN

plot commands

data value corresponding to the start of the vertical axis

YAXIS_MAX

plot commands

data value corresponding to the end of the vertical axis

LABKEY

line PLOT, POLYGON

text for key of latest line or polygon put on the plot

VP_HEIGHT

SET VIEWPORT

height of current viewport

VP_WIDTH

SET VIEWPORT

width of current viewport

VP_XLO

SET VIEWPORT

lower x corner of viewport, as defined by DEFINE VIEWPORT/XLIM=xlo:xhi

VP_XHI

SET VIEWPORT

upper x corner of viewport, as defined by DEFINE VIEWPORT/XLIM=xlo:xhi

VP_YLO

SET VIEWPORT

lower y corner of viewport, as defined by DEFINE VIEWPORT/YLIM=ylo:yhi

VP_YHI

SET VIEWPORT

upper y corner of viewport, as defined by DEFINE VIEWPORT/YLIM=ylo:yhi

VP_RT_MARGIN

SET VIEWPORT

width of right margin(see ppl$xorg for left margin)

VP_TOP_MARGIN

SET VIEWPORT

width of top margin(see ppl$yorg for lower margin)

VP_SCALE

SET VIEWPORT

shrinking or expansion factor see DEFINE VIEWPORT/TEXT

LEV_TEXT

CONTOUR, SHADE

command argument used to set levels.

LEV_MIN

CONTOUR, SHADE

minimum contour level used

LEV_MAX

CONTOUR, SHADE

maximum contour level used

LEV_NUM

CONTOUR, SHADE

number of levels used

LEV_DEL

CONTOUR, SHADE

delta-value between levels



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