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.