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Illustrating a Maths Function

This deceptively simple chart was drawn to illustrate the shape of the Logistic Distribution.


It is important for this kind of chart that the finished graphic accurately preserves the proportions of the original, so that circles stay circular, however you display or print them (see Circle for another example). Rain takes great care to ensure you have detailed control over the plotting space. Note the use of the Symbol font to get the Greek gamma character as a note.

In this case, I wanted a narrow plot to fit down the side of a printed page (note that when you export a plot as a .EPS file, Rain adds ‘BoundingBox’ information so that your DTP software will get the shape right) and I did not need margins above or to the right.

 R„ASL91;PACK;FIT 
© VECTOR ASL example 
 PACK„6+0.1×¼120 
 FIT„100×÷1+*(12-PACK)÷1.31 
 ch.New 0 0 210 324 ª ch.Set('Colour' 'neutral')('Nibs' 'broad') 
 ch.Set('Style' 'Nomark')('Vmar' 48 0)('Hmar' 24 0) 
 ch.Set'Hstyle' 'right' 
 ch.Set('Xstyle' 'plain')('Xcap' 'z') 
 ch.Set('Ytick' 50 100)('Ycap' 'Optical Density y')('Ylab' '0,0.5v,v') 
 ch.Set('Cfont' 'TI,14')('Nfont' 'SY,14')('Lfont' 'TI,14') 
 ch.Set('Xdatum' 60)('Ydatum' 50 100) 
 ch.Plot FIT 
 ch.Note'-g'(56 ¯4) 
 PG„ch.Close 
 R„'View PG © to see it'


Continue to: The Gilling East Rainfall Chart
© Copyright Causeway Graphical Systems Ltd 2003