A Singular Surface

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This animation depicts a standard surface from multivariable calculus. (See notes below.)


The surface shown here is given by the equation z = 2 x y ⁄ (x2 + y2), or, in cylindrical coordinates, z = sin(2θ). Note that approaching the origin along the ray θ = θ0 gives a limiting value of z = sin(2θ0), so that the surface cannot be continuous at the origin. (11/27/07)