design/invalid4.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 # Check a-posteriori the sign of Delta y for the square-root solution of Delta x
   7
   8 def Dx_m(y):
   9     return (-1-2*y-sqrt((1+2*y)**2+3))/3.0
  10 def Dx_p(y):
  11     return (-1-2*y+sqrt((1+2*y)**2+3))/3.0
  12
  13 con = {"Dx_m":Dx_m, "Dx_p":Dx_p}
  14
  15 g = graph.graphxy(width=10,
  16     x=graph.axis.lin(),
  17     y=graph.axis.lin(min=-2, max=2),
  18     key=graph.key.key(pos="bl"),
  19 )
  20 g.plot(graph.data.function("x(y)=6*y*Dx_m(y)", title="minus-sol, lhs", context=con), [graph.style.line([color.rgb.red])])
  21 g.plot(graph.data.function("x(y)=(1-3*Dx_m(y))*(1-y-sqrt(1+y+y*y))", title="minus-sol, minus-rhs", context=con), [graph.style.line([color.rgb.blue, style.linestyle.dashed])])
  22 g.plot(graph.data.function("x(y)=6*y*Dx_p(y)", title="plus-sol, lhs", context=con), [graph.style.line([color.rgb.green])])
  23 g.plot(graph.data.function("x(y)=(1-3*Dx_p(y))*(1-y+sqrt(1+y+y*y))", title="plus-sol, plus-rhs", context=con), [graph.style.line([style.linestyle.dashed])])
  24 g.plot(graph.data.function("x(y)=(1-3*Dx_p(y))*(1-y-sqrt(1+y+y*y))", title="plus-sol, minus-rhs", context=con), [graph.style.line([style.linestyle.dotted])])
  25 g.plot(graph.data.function("x(y)=(1-3*Dx_m(y))*(1-y+sqrt(1+y+y*y))", title="minus-sol, plus-rhs", context=con), [graph.style.line([style.linestyle.dotted])])
  26 g.writePDFfile()
  27