The argument principle states that, for a meromorphic function f and a closed curve γ, the contour integral of f'/f on γ is equal to the number of zeros minus the number of poles enclosed by γ. This is equivalent to the statement that the winding number f(γ) around the origin equals the number of zeros minus the number of poles enclosed by γ.
Left-drag on the z-plane to draw a closed curve.
Right-drag to pan. Scroll to zoom.
Without drawing, a circle of radius r follows the cursor.
Use z, i, pi, and
sin cos tan exp log sqrt with ^ for powers.