Plotting math functions

Ctioga knows basic math function from which a lot can already be done. Let’s plot an exponential:

 ctioga --math 'exp(x)'

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Note that the variable in the function is always implicitly “x”

By the way, let’s not forget to add some title via the --title (or -t) command

 ctioga --math 'exp(x)' --title 'My exponential'

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By default Ctioga assumes that the x-range is -10:10 and stretches the y-axes so that the function is completely in the plot. A more “usual” way of looking at exponentials could be

 ctioga --math-xrange -5:1 --math 'exp(x)' -t 'My exponential'

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Note that you have to use --math-xrange to get this behavior, the --xrange option will only modify the plotting range but not the computing range, which could lead to sampling problems. Compare

 ctioga --xrange -1:1 --math 'sin(10 * x)' \
        -t 'badly sampled sine'

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and

 ctioga --math-xrange -1:1 --math 'sin(10 * x)' \
        -t 'well sampled sine'

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From time to time, it can be very useful to define a function piece by piece:

 ctioga --xrange -3:3 --math-xrange -2:0 --math 'x+1'    \
                      --math-xrange 0:2         'exp(x)' \
                      -t 'Strange exponential'

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Adding the --yrange option can be used to isolated a piece of graph

 ctioga --yrange -2:8 --xrange -3:3         \
        --math-xrange -2:0 --math 'x+1'     \
        --math-xrange  0:2        'exp(x)'  \
        -t 'Strange exponential'

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Ctioga also knows about parametric functions, whenever you use the variable t,

 ctioga --math --math-trange -3.1415:3.1415 \
        'sin(2*t):cos(3*t)'                 \
        -t 'parametric curve'

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Note that you can use --math-trange to specifies the range over which to compute the curve. As for --math-xrange, default is -10:10.

--include options allows you to define some functions so that ctioga could use them. Look to file include_1.rb for an example of syntax. In this file is defined the function pol(x) = (1.0 - x) * (1.0 + x) that we can use:

 ctioga --include include_1.rb --math 'pol(x)' -t 'Polynomial function'

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