On Thursday 27 November 2008 22:03:57 Ondrej Certik wrote:
> This looks good to me. Could you please also create more tests for the
> line_integrate? You can add them as additional patches.
>
> Ondrej
>
> On Thu, Nov 27, 2008 at 9:57 PM, Ondrej Certik <[EMAIL PROTECTED]> wrote:
> > From: Priit Laes <[EMAIL PROTECTED]>
> >
> > ---
> > sympy/integrals/__init__.py | 2 +-
> > sympy/integrals/integrals.py | 45
> > +++++++++++++++++++++++++++ sympy/integrals/tests/test_lineintegrals.py |
> > 9 +++++
> > 3 files changed, 55 insertions(+), 1 deletions(-)
> > create mode 100644 sympy/integrals/tests/test_lineintegrals.py
> >
> > diff --git a/sympy/integrals/__init__.py b/sympy/integrals/__init__.py
> > index 6027264..7abce35 100644
> > --- a/sympy/integrals/__init__.py
> > +++ b/sympy/integrals/__init__.py
> > @@ -5,4 +5,4 @@ Out[3]: log(x)
> > In [4]: integrate(sin(x),x)
> > Out[4]: -cos(x)
> > """
> > -from integrals import integrate, Integral
> > +from integrals import integrate, Integral, line_integrate
> > diff --git a/sympy/integrals/integrals.py b/sympy/integrals/integrals.py
> > index 8094919..d541569 100644
> > --- a/sympy/integrals/integrals.py
> > +++ b/sympy/integrals/integrals.py
> > @@ -10,6 +10,7 @@ from sympy.series import limit
> > from sympy.polys import Poly
> > from sympy.solvers import solve
> > from sympy.functions import DiracDelta, Heaviside, Piecewise
> > +from sympy.geometry import Curve
> >
> > class Integral(Basic):
> > """Represents unevaluated integral."""
> > @@ -377,3 +378,47 @@ def integrate(*args, **kwargs):
> > return integral.doit()
> > else:
> > return integral
> > +
> > +
> > [EMAIL PROTECTED](use_add=False)
> > +def line_integrate(field, curve, vars):
^^^
> > + """line_integrate(field, Curve, variables)
> > +
> > + Compute the line integral.
> > +
> > + Examples
> > + --------
> > + >>> from sympy import *
> > + >>> x, y, t = symbols('xyt')
> > + >>> C = Curve([E**t + 1, E**t - 1], (t, 0, ln(2)))
> > + >>> line_integrate(x + y, C, [x, y])
> > + 3*sqrt(2)
> > +
> > + """
> > + F = sympify(field)
> > + if not F:
> > + raise ValueError("Expecting function specifying field as first
> > argument.") + if not isinstance(curve, Curve):
> > + raise ValueError("Expecting Curve entity as second argument.")
> > + if not isinstance(vars, (list, tuple)):
> > + raise ValueError("Expecting list/tuple for variables.")
> > + if len(curve.functions) != len(vars):
> > + raise ValueError("Field variable size does not match curve
> > dimension.") +
> > + if curve.parameter in vars:
> > + raise ValueError("Curve parameter clashes with field
> > parameters.") +
> > + # Calculate derivatives for line parameter functions
> > + # F(r) -> F(r(t)) and finally F(r(t)*r'(t))
> > + Ft = F
> > + dldt = 0
> > + for i, var in enumerate(vars):
> > + _f = curve.functions[i]
> > + _dn = diff(_f, curve.parameter)
> > + # ...arc length
> > + dldt = dldt + (_dn * _dn)
> > + Ft = Ft.subs(var, _f)
> > + Ft = Ft * dldt**(S(1)/2)
> > +
> > + integral = Integral(Ft, curve.limits).doit()
> > + return integral
> > diff --git a/sympy/integrals/tests/test_lineintegrals.py
> > b/sympy/integrals/tests/test_lineintegrals.py new file mode 100644
> > index 0000000..1cb8a8c
> > --- /dev/null
> > +++ b/sympy/integrals/tests/test_lineintegrals.py
> > @@ -0,0 +1,9 @@
> > +from sympy import (symbols, integrate, Integral, diff, sin, cos, pi, E,
> > ln, + sympify, Curve, line_integrate, sqrt)
> > +
> > +s, t, x, y, z = symbols('stxyz')
> > +
> > +def test_lineintegral():
> > + c = Curve([E**t + 1, E**t - 1], (t, 0, ln(2)))
> > + assert line_integrate(x + y, c, [x, y]) == 3*sqrt(2)
> > +
> > --
> > 1.6.0.4
Nice patch!
Just a comment: vars is a python keyword, I think is better to change it to
something better.
Sorry for the late review!
Cheers,
Riccardo
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