Solving an equation on the HP50G (as compared to the Prime)

[RMollov]

(07-20-2019 05:51 AM)rrpalma Wrote:  Hello,

Long time HP50G user, but started using the Prime a couple of months ago -- and I find that I quite like it!

Anyways, on page 6-13 of the HP50G User's Guide there is an example of an equation to be solved:

exp(x) - sin((pi*x)/3) = 0

The guide uses the Numerical Solver to solve this equation, and provides 4.5006E-2 as an example solution -- as also found on the HP50G. This however, does not seem to be a correct solution to the equation, for when it is substituted for x on the left side of the equation, we don't get 0.

However, when solved on the Prime, with an initial guess of 1, an initial (correct) solution of {−3.04544793088} is obtained.

Any ideas on how to solve this on the HP50G?

Thanks!!!!

You need to specify interval to find a solution in, then figure out the result. If you supply x as {-10 0}
solver gives -3.04544793089 Sign Reversal, with 0: - 4.50061385902E-2 Extremum. It's up to you to decide which answer to use.

You could also plot it and select interval there.
HP50 and Prime have different accuracy therefore the two sides of equation may differ.
BTW DM42 finds 'exact' solutions at sign reversal points like:
-3.045447930881649697415605577746648
-5.997627340756129979223366652843795
-9.000117833796755710867792548726015
and others