design/invalid1.py

   1 #!/usr/bin/env python
   2 import sys;sys.path.insert(0, "..")
   3 from math import *
   4 from pyx import *
   5 # File for invalid parametrisations of Bezier curves
   6 # visualise the constraints
   7
   8 def fx(x, sign1):
   9     if x < 1/3.0: # a_x > 0
  10         if sign1 == "upper":
  11             return -x + abs(x)
  12         else:
  13             return -x - abs(x)
  14     else:
  15         if sign1 == "upper":
  16             return x - abs(x)
  17         else:
  18             return x + abs(x)
  19
  20 def boundx(x):
  21     if x < 1/3.0:
  22         return 1-3*x
  23     else:
  24         return 3*x-1
  25
  26 def fy(y, sign2):
  27     if y < 0: # a_y > 0
  28         if sign2 == "upper":
  29             return 1-y + sqrt(1+y+y*y)
  30         else:
  31             return 1-y - sqrt(1+y+y*y)
  32     else:
  33         if sign2 == "upper":
  34             return y-1 - sqrt(1+y+y*y)
  35         else:
  36             return y-1 + sqrt(1+y+y*y)
  37
  38 def boundy(y):
  39     if y < 0:
  40         return -3*y
  41     else:
  42         return 3*y
  43
  44 def doplot(xtitle, con):
  45     g = graph.graphxy(width=10,
  46         x=graph.axis.lin(title=xtitle, min=-5, max=5),
  47         y=graph.axis.lin(),
  48         key=graph.key.key(pos="tc"),
  49     )
  50     g.plot(graph.data.function("y(x)=0", points=2, title=None), [graph.style.line()])
  51     g.plot(graph.data.function("y(x)=bound(x)", title=None, context=con, points=101), [graph.style.line()])
  52     g.plot(graph.data.function("y(x)=f(x, 'upper')", title="upper sign", context=con, points=101), [graph.style.line([color.rgb.red])])
  53     g.plot(graph.data.function("y(x)=f(x, 'lower')", title="lower sign", context=con, points=101), [graph.style.line([color.rgb.green])])
  54     return g
  55
  56
  57 c1 = doplot(r"$\Delta x$", {"f":fx, "bound":boundx})
  58 c2 = doplot(r"$\Delta y$", {"f":fy, "bound":boundy})
  59 c1.insert(c2, [trafo.translate(0, c1.bbox().bottom() - c2.bbox().top() - 0.5)])
  60 c1.writePDFfile()