next surface | previous surface | 2D curves | 3D curves | surfaces | fractals | polyhedra |
BISPHERICAL ALGEBRAIC SURFACE
An algebraic surface is said to be bispherical if the umbilics (i.e. the points at infinity of the complex sphere with zero radius ) form a double line, in the complex projective completion of the space.
The necessary and sufficient condition is that the polynomial composed of the terms with highest degree n of its Cartesian equation be divisible by and that the polynomial composed of the terms of with degree n - 1 be divisible by .
The bispherical quartics are the Darboux cyclides.
next surface | previous surface | 2D curves | 3D curves | surfaces | fractals | polyhedra |
© Robert FERRÉOL 2017