As you can see, I have attempted Goursat [Gobstopper]... not to avail.
Will try again from the Mathcad program, via Spline Matrix => f(u,v).

Jean

Rotate Goursat.sm (384 KiB) downloaded 137 time(s).

Hello, Jean. The algorithm is only suitable for constructing simply-connected
Surfaces without singular points. Therefore, for the first surface it
not approached, and the second turned out to be of poor quality.
The second surface and its upper half, constructed with the help of the
new algorithm.


GoursatJean.sm (28 KiB) downloaded 116 time(s).

Thanks Ber7 for the explanation.
Will come back, because very slow on my Win 7 ...

Jean

Wrote

Hello, Jean. The algorithm is only suitable for constructing simply-connected
Surfaces without singular points. Therefore, for the first surface it
not approached, and the second turned out to be of poor quality.
The second surface and its upper half, constructed with the help of the
new algorithm.


GoursatJean.sm (28 KiB) downloaded 116 time(s).

Such a graph is possible only for a>0
(x1*x2)^2+(x2*x3)^2+(x1*x3)^2 - a=0;