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# Data plotting

#### Introduction

After a call to ``` frame ```, one can in several ways visualise (X,Y)-data specified by NP points. DLAB, NP, XA and YA are common parameters of the data plotting routines.

DLAB (string)
is a label describing the data. DLAB is displayed the legend together with an indication of the way the data are drawn. (UNIX workstations <= 48 characters, Cray <= 64 characters)
XA (real array)array containing the X-coordinates of the NP points. YA (real array)array containing the Y-coordinates of the NP points. NP (integer <= 10000)the number of points to plot. The lower bound of NP depends upon the visualisation method. Mind that the total number of points of a complete graph is also 10000.

The mapping of the coordinates to the axes is defined by frame. If desired, the coordinates are used to compute automatically the axis numbers. For a logarithmic axis, Komplot performs the 10 logarithmic transformation of the coordinates. Coordinates <= 0.0 are omitted! PostScript line width and grayvalue can be changed.

#### Lines

`POLYLINE (DLAB, NP, XA, YA)`
Successive points are connected by straight lines. NP>=2.
`DISJOINT_LINE (DLAB, NP, XA, YA)`
Point 1 and 2, 3 and 4, 5 and 6, ... are connected by straight lines. NP>=2.

#### Interpolation

`CURVE (DLAB, NP, XA, YA)`
Successive points are connected by a smooth interpolated curve (Akima interpolation). NP>=3
`CLOSED_CURVE (DLAB, NP, XA, YA)`
Same as CURVE, but last point connected to first point.
(`SPLINE (DLAB, NP, XA, YA)` )

#### Markers, errorbars

`MARKERS (DLAB, NP, XA, YA, ISYM)`
All points are plotted with a marker defined by ISYM. NP>=1. ISYM is an integer chosen from the table.
`SCALE_MARKERS(scale_factor)`
The height of the markers (default 0.21 cm) can be scaled with `Scale_markers`. It must be called before `frame`!
`V_ERRORBARS (DLAB, NP, XA, YA, EA)`
Vertical errorbars, specified by the real array EA, are drawn. Point I has an errorbar from YA(I)-EA(I) to YA(I)+EA(I). Errorbars are automatically transformed for a logarithmic axis.
`H_ERRORBARS (DLAB, NP, XA, YA, EA)`
Horizontal errorbars, specified by the real array EA, are drawn. Point I has errorbar from XA(I)-EA(I) to XA(I)+EA(I). Errorbars are automatically transformed for a logarithmic axis.
`VAR_MARKERS (DLAB, NP, XA, YA, ISYMA)`
Each point has its own marker type specified by the integer array ISYMA. NP>=1.
`VAR_SCALE_MARKERS (DLAB, NP, XA, YA, ISYM, SA)`
All points are marked by the same marker defined by ISYM, but the height of separate markers are scaled by values in the real array SA. 0.1<=SA(I)<10.0. NP>=1.

#### Approximation

`LOCAL_PARABOLA_AP (DLAB, NP, XA, YA, NREPEAT)`
Local parabola fitting (Lanczos) on 5 successive points. The process is repeated NREPEAT times. NP>=5, X-coordinates equidistant.
`SPLINE_AP (DLAB, NP, XA, YA, SSQ)`
Cubic spline approximation with knots same as X-coordinates of points. SSQ is the sum of squares of deviations and controls the approximation. SSQ = 0 : interpolation. NP>=5.
`W_SPLINE_AP (DLAB, NP, XA, YA, WA, SSQ)`
Same as before, but now points have weighting factors in the real array WA.
`SPLINE_VAR_KNOTS_AP (DLAB, NP, XA, YA, NK, XKA)`
`W_SPLINE_VAR_KNOTS_AP (DLAB, NP, XA, YA, WA, NK, XKA)`

#### Bardiagram

`BARS (DLAB, NP, XA, YA, IFILL, WIDTH)`
(XA(I), YA(I)) defines the centre of the top line of bar I. NP>=1.
`WIDTH `(real)
is the barwidth
`IFILL` (integer)
defines the filling as shown in the tabel

#### Fill area

`FILL_AREA (DLAB, NP, XA, YA, IFILL)`
An area defined by NP points (last point connected to first point) is filled according to the value of IFILL, see Bardiagram. NP>=3
PS_FILL_AREA (DLAB, NP, XA, YA)
An area defined by NP points (last point connected to first point) is filled at a PostScript printer with a gray value defined by . A next call must define linewidth and grayvalue of following Komplot calls. NP>=3

## Final remarks

• Parts of the data outside the border are cut off (clipped).
• line type ..., line style ...
• abs(NP) = number of points.
NP > 0 : coordinates in units defined by `frame `
NP < 0 : coordinates expressed in cm relative to the origin
• DLAB can be empty : no label in legend.
• If the first character of DLAB is a minus sign (-), which is not plotted, no indication of the data is plotted before DLAB in the legend.
• `SUPPRESS_ERRORBAR_CROSSLINES(L)` can be used to change errorbars.