Re: HP 35S  2*2 lin. solve bug Message #5 Posted by Palmer O. Hanson, Jr. on 16 Jan 2010, 10:11 p.m., in response to message #1 by Maarten Ambaum (Reading, UK)
My first idea was that the 35s program used a methodology somewhat like that in the "Solution of Simultaneous Equations" program on pages 1512 through 1520 of the hp 33s use's guide which solves the 2x2 case by placing zeroes and a one in appropriate positions of the 3x3 solver. But some testing tells me that doesn't seem to be true.
The 3x3 equation seems to work properly even if a vector or a complex number is stored somewhere in registers M through Z. But, neither the 2x2 nor the 3x3 equation will solve with complex number inputs, even though the following comment from page 97 of the HP35s User's Guide would seem to indicate that it should:
Quote:
When you evaluate an equation and are prompted for variable values, you may enter complex numbers.
So, I conclude that the programmer recognized that his programs would not work with complex numbers and included a trap to alert a user of an unacceptable input, which resulted in a failure of the 2x2 solution if there was a leftover complex number in registers G theough L.
Strange stuff indeed.
Edited: 17 Jan 2010, 9:43 p.m.
