title spring

c  MESH - in cylindrical coordinates

cylinder 1 5 ; 1 79 80 81 82 249 250 251 252 331 ; 1 5 ;
 1.8 2.2 0 312 316 320 324 992 996 1000 1004 1320 -.2 .2

c  project onto a torus

sfi -1 -2 ; ; -1 -2 ; ts 0 0 0 0 0 1 2 0 .2

c  strech the periodic torus to form a helix

dom 1 1 1 2 2 2
 z = z + 4.05
dom 1 2 1 2 2 2
 z = z - 4.05
dom 1 2 1 2 5 2
 z = z + 4.05 + 0.05*(j-79)/3
dom 1 5 1 2 5 2
 z = z - 4.1
dom 1 5 1 2 6 2
 z = z + 0.05*j
dom 1 6 1 2 6 2
 z = z - 12.45
dom 1 6 1 2 9 2
 z = z + 12.45 + 0.05*(j-249)/3
dom 1 9 1 2 9 2
 z = z - 12.5
dom 1 9 1 2 10 2
 z = z + 12.5
endpart
merge
rx 50 zf 1.5 tvv
