graph program at CDS

For a full functionality of the graphical output of the data from VizieR, a few new features were added at CDS:

  1. A few new options:

    • –x and –y options (defining the range of values) accepts dashes in the 3 numbers min max spacing. Specifying e.g. –y – – – means that the y axis increases toward to bottom (required for light curves with units in mag).

    • –I (input type) accepts the value s when points have error bars on both x and y; this new option requires 4 values for each point: x, y, σ(x), σ(y).

    • –T accepts the txt value to just print out the values to the standard output.

  2. A more flexible way for the ascii input:
    • in case of invalid values (e.g. infinity, NaN) in any of its components (x, y, σ(x), σ(y)) the point is discarded (and and error message is written on the standar error)

    • Specifying a new mode for the graph in the input data can be achieved by writing in the input the parameter without blanks:
      • m=value   (change of mode)
      • S=value   (change of symbol)
      • I=value   (change of input type) value make take the values a (ascii, just 2 coordinates per point), e or y (error bar on y-axis), x (error bar on x-axis), and s (both σ(x) and σ(y) given).
      The changes still work with the tradition way of a line with the format
      # m = %f S = %s I = %c
      but the blanks before and after the equal signs are not required.

  3. Possibility of writing text on the plot.

    An example is:

    # m=3 put[+2cmU](0.5,0.5) Center

    the text Center will be written in the middle of the graph (the coordinates are written within parentheses); the font size, the text orientation and justification are given within brackets, and here the font is magnified 2 times (+2), the text is oriented to the top (U), centered horizontally (c) and vertically (m).

    Note that a mode (3 in the example) may be given to choose the line mode; it is esentially used to chose the color, 3 corresponding to blue (unless modified by the –pen-colors option).

    The meanings of the various parameters within the square brackets are:

    • magnification: acceptable values in the range [–4⋅⋅⋅+4], where a change of step corresponds to a factor 1.2 (around 21/4). The value 0 corresponds to the size of the title.

    • direction is specified by one of the 4 uppercase letters L R U D for left, right, up and down orientation; the default is R.

    • horizontal justification is specified by one of the 3 letters l r c for left, right and center; l is the default.

    • vertical justification is specified by one of the 4 letters t b m x for top, bottom, middle (center) and baseline. x is the default.

    The font used and default size are those of the title (label), i.e. specified in the program graph with the arguments –title-font-name and –title-font-size.

  4. Possibility of using TEX-way for texts

    The various texts (captions along the axes, label of the plot) may be specified using the TEX conventions, which are especially simpler to express exponents and indices. Another convention, the soft-TEX is also usable.

    The convention is that, when the text to write on the plot starts by the sequence

    • ^ (carret-blank) a TEXized text is assumed;
    • ^^ (2 carrets) a soft-TEX is assumed.

    The main difference is in the way of specifying indices and exponents: e5+α would be written e^{5+\alpha} in the TeX-way, but e^5+{alpha}^ in the soft-TEX way, which uses the carret at both beginning/end of the exponent. For indices, the undercore (_) is used in place of the carret (^).

© Université de Strasbourg/CNRS

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