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#### 8.3.32 `function`

Plots an analytic function. This layer is currently only available for the Plane plots (including histogram).

Usage Overview:

       layerN=function axisN=Horizontal|Vertical xnameN=<name> fexprN=<expr>
                       colorN=<rrggbb>|red|blue|... thickN=<pixels>
                       dashN=dot|dash|...|<a,b,...> antialiasN=true|false

All the parameters listed here affect only the relevant layer, identified by the suffix `N`.

Example:

       stilts plot2plane layer1=function fexpr1=sin(x)/x thick1=3
                         xmin=0 xmax=30 ymin=-0.25 ymax=0.25

`antialiasN = true|false` (Boolean)
  If true, plotted lines are drawn with antialising. Antialised lines look smoother, but may take perceptibly longer to draw. Only has any effect for bitmapped output formats.

  [Default: `false`]

`axisN = Horizontal|Vertical` (FuncAxis)
  Which axis the independent variable varies along. Options are currently `Horizontal` and `Vertical`.

  [Default: `Horizontal`]

`colorN = <rrggbb>|red|blue|...` (Color)
  The color of plotted data, given by name or as a hexadecimal RGB value.

  The standard plotting colour names are `red`, `blue`, `green`, `grey`, `magenta`, `cyan`, `orange`, `pink`, `yellow`, `black`, `light_grey`, `white`. However, many other common colour names (too many to list here) are also understood. The list currently contains those colour names understood by most web browsers, from `AliceBlue` to `YellowGreen`, listed e.g. in the Extended color keywords section of the CSS3 standard.

  Alternatively, a six-digit hexadecimal number RRGGBB may be supplied, optionally prefixed by "`#`" or "`0x`", giving red, green and blue intensities, e.g. "`ff00ff`", "`#ff00ff`" or "`0xff00ff`" for magenta.

  [Default: `red`]

`dashN = dot|dash|...|<a,b,...>` (float[])
  Determines the dash pattern of the line drawn. If null (the default), the line is solid.

  Possible values for dashed lines are `dot`, `dash`, `longdash`, `dotdash`. You can alternatively supply a comma-separated list of on/off length values such as "`4,2,8,2`".

`fexprN = <expr>` (String)
  An expression using TOPCAT's expression language in terms of the independent variable to define the function. This expression must be standalone - it cannot reference any tables.
`thickN = <pixels>` (Integer)
  Thickness of plotted line in pixels.

  [Default: `1`]

`xnameN = <name>` (String)
  Name of the independent variable for use in the function expression. This is typically `x` for a horizontal independent variable and `y` for a vertical independent variable, but any string that is a legal expression language identifier (starts with a letter, continues with letters, numbers, underscores) can be used.

  [Default: `x`]

Next Previous Up Contents
Next: skyvector
Up: Layer Types
Previous: gaussian

STILTS - Starlink Tables Infrastructure Library Tool Set
Starlink User Note256
STILTS web page: http://www.starlink.ac.uk/stilts/
Author email: m.b.taylor@bristol.ac.uk
Mailing list: topcat-user@jiscmail.ac.uk