Plot a function with matplotlib?

[Alex van der Spek]

On Sat, 19 May 2012 01:59:59 +0000, Steven D'Aprano wrote:

> I have matplotlib and iPython, and want to plot a function over an
> equally-spaced range of points.
> 
> That is to say, I want to say something like this:
> 
> plot(func, start, end)
> 
> rather than generating the X and Y values by hand, and plotting a
> scatter graph. All the examples I've seen look something like this:
> 
> from pylab import *
> import numpy as np
> t = arange(0.0, 2.0+0.01, 0.01)  # generate x-values s = sin(t*pi)  #
> and y-values
> plot(t, s)
> show()
> 
> 
> which is fine for what it is, but I'm looking for an interface closer to
> what my HP graphing calculator would use, i.e. something like this:
> 
> 
> plot(lambda x: sin(x*pi), # function or expression to plot,
>      start=0.0,
>      end=2.0,
>     )
> 
> and have step size taken either from some default, or better still,
> automatically calculated so one point is calculated per pixel.
> 
> Is there a way to do this in iPython or matplotlib?

Not to my knowledge unless you code it yourself.

However in gnuplot (www.gnuplot.info)

gnuplot>>> set xrange[start:end]
gnuplot>>> foo(x)=mycomplicatedfunction(x)
gnuplot>>> plot foo(x)

or shorter still

gnuplot>>> plot [start:end] foo(x)

without the need to set the xrange in advance.