descartes: an image, data, and function plotter 
hosted by 
Mathematical functions are handled by the Python interpreter. In the good and in the bad, syntax and semantics follow Python conventions. Use ** for exponentiation. Be prepared that 1/3 is evaluated as 0 because in Python division of two integers always returns an integer value. To force floating point evaluation, type 1.0/3 or 1./3 for short. Mathematical functions from Python's math module can be used in function terms; these include exp, log (natural logarithm), log10 (decadic logarithm), sin, cos, tan.
Descartes' mathematical capabilities can be extended through a plugin mechanism. Use the File>Plugin option in the control window to include your own Python code which may contain function definitions like the following: global R def R(x): if x<1: return 1 elif x<0: return x elif x<1: return x else: return 1
Input of xydata is possible from CSV files. While CSV originally means comma separated, descartes allows also for semicolon, tab, and white space as separators. The first line of the CSV file may contain the names of x and y coordinates, enclosed in doublequotes. See demo/bulb.csv for an example of a valid CSV file.
