A case against the x<>y key

[Steve Simpkin]

(05-10-2015 09:44 PM)Mark Hardman Wrote:  

(05-10-2015 09:32 PM)Steve Simpkin Wrote:  Does anyone know of an example in a HP produced manual that shows an example of this type of problem?

There is the famous Mach number equation from the HP-67/97 manual:

\[\sqrt{ 5 \left [ \left ( \left \{ \Bigg [ \Bigg ( 1 + 0.2 \left [ \frac{350}{661.5} \right ]^{2} \Bigg )^{3.5} - 1 \Bigg ] \Bigg [ 1 -\left ( 6.875 \times 10^{-6} \right ) 25,500 \Bigg ] ^{-5.2656}\right \} + 1 \right )^{0.286} -1 \right ]}\]

I remember that problem very well from the HP-25 manual as well. I think it doesn't have the same type of potential "trap" as the OP had in their example. The solution shown in the HP manual for the Mach problem did not use the X<>Y key for the "1-" area of the problem but I believe they could have used it in this case without issue.