HELIX - SPIRAL SPECIFICATION (GH)

 Purpose: To generate a helix or spiral of wire segments
 Card:

            Cols        Parameter
           ----------------------
            1- 2        GH
            3- 5        I1 - ITG
            6-10        I2 - NS
           11-20        F1 - S
           21-30        F2 - HL
           31-40        F3 - A1
           41-50        F4 - B1
           51-60        F5 - A2
           61-70        F6 - B2
           71-80        F7 - RAD

 Parameters:

       Integers

            ITG (11) - Tag number assigned to all segments of the helix or
                         spiral.

            NS (12) - Number of segments into which the helix or spiral
                         will be divided.

       Decimal Numbers

            S    (F1) - Spacing between turns.

            HL   (F2) - Total length of the helix.

            A1   (F3) - Radius in x at z = 0.

            B1   (F4) - Radius in y at z = 0.

            A2   (F5) - Radius in x at z = HL.

            B2   (F6) -  Radius in y at z = HL.

            RAD  (F7) -  Radius of wire.

  Notes:

              1. Structure will be a helix if A2 = A1 and HL > 0.

              2. Structure will be a spiral if A2 = A1 and HL = 0.

              3. HL negative gives a left-handed helix.

              4. HL positive gives a right-handed helix.