Rules of Transposition 2 using Syah's Rules

Last post, I've shared rules of transposition of minus cyl form to plus cyl form or vise versa. This time, I would like to share rules of transposition of spherical form to spherocyl form (-ve cyl and +ve cyl). By using these rules, you do not need to draw the cross-line diagram.

Rules of Transposition

Do you know that we have simple rules to transpose minus (-ve negative) cylinder form to plus (+ve positive) cylinder form and vice versa? Just follow these rules below, InsyaAllah, you will always obtain a correct answer.

Rules of transposition

1.Add the sph and cyl, taking into account their sign

2.Change their sign of the cyl

3.Alter the axis by 90°

  a. if the original axis is 90° or less, add 90° to it

  b. if the original axis is over 90°, subtract 90° from it