a := 1.5
a.minium := -4
a.maximum := 4
b := 0.2
b.minimum := -4
b.maximum := 4
graph3d.box := false
graph3d.mesh := false
graph3d.view := standard
graph3d.perspective := true
graph3d.resolution := 40
graph3d.highlight := 1
graph3d.shading := 1
graph3d.contrast := 1/2
graph3d.transparency := 0
graph3d.color := bysteepness
graph3d.minimumx := -4
graph3d.maximumx := 4
graph3d.minimumy := -4
graph3d.maximumy := 4
graph3d.minimumz := -4
graph3d.maximumz := 4
graph3d( x^2+y^2+z^2^+a^2-b^2=2*a*sqrt(x^2+y^2))