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
>
>
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