u := x (4 - y - x^2)(adsbygoogle = window.adsbygoogle || []).push({});

v := y (-1 + x)

(-2,0)

du := (4 - y - 3 x^2) dx - x dy

dv := y dx + (-1 + x) dy

x := -2 + Cos[\[Theta]]

y := 0 + Sin[\[Theta]]

dx := -Sin[\[Theta]]

dy := Cos[\[Theta]]

Integrate[1/(2 \[Pi]) Expand[(u dv - v du)/(u^2 + v^2)], {\[Theta], 0,

2 \[Pi]}]

If you copy and paste that into mathematica, I'm supposed to get either 1 or -1 but it doesn't work. Does anyone know why?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Numerical Integration

**Physics Forums | Science Articles, Homework Help, Discussion**