cylinder cyl 0 0 0 1 1 1 1
mkface f cyl 0 2 0 1
explode f w
nurbsconvert w f_1
cylinder cyl 0.1 0.1 0.1 1 1 1 .9
getanasurf res w cyl 1.e-3 cyl
if {[isdraw res]} {
  set log [dump res]
  if { [regexp {CylindricalSurface} $log ] != 1 } {
     puts "Error: surface is not a cylindrical surface"
  }
} else {
  puts "Error: required surface is not got"
}