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 15-12 through 15-20 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 9-7 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.
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