Hi,

I read and entered this program here, after finding his Quadratic solver using ACOSH nice to use.

"Solving a cubic equation using trigonometry" by *Thomas Klemm*

http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv020.cgi?read=180771

A general cubic equation can be transformed to the following form using a substitution;

00 { 31-Byte Prgm } 00 { 34-Byte Prgm }

01>LBL "CuEq" 01>LBL "CuEqH"

02 2 02 2

03 / 03 /

04 X<>Y 04 X<>Y

05 -3 05 3

06 / 06 /

07 / 07 /

08 LASTX 08 LASTX

09 SQRT 09 SQRT

10 / 10 /

11 LASTX 11 LASTX

12 X<>Y 12 X<>Y

13 ASIN 13 ASINH

14 3 14 3

15 / 15 /

16 SIN 16 SINH

17 * 17 *

18 2 18 -2

19 * 19 *

20 END 20 END

However, it doesn't work if you have an a2 term, unless I've made a typo. Having to do substitution before using the program seems to defeat the purpose.

Daniel.