HP 15C Manuale Utente Scaricare il pdf (Pagina 230)

230 Appendix D: A Detailed Look at _

If the algorithm terminates its search near a

local minimum of the function's magnitude,

clear the Error 8 display and observe the

numbers in the X-, Y-, and Z-registers by

rolling down the stack. If the value of the

function saved in the Z-register is relatively

close to zero, it is possible that a root of

your equation has been found  the number

returned in the X-register may be a 10-digit

number very close to a theoretical root. You

can explore this potential minimum further by rolling the stack until the

returned estimates are back in the X- and Y-registers and then executing

_ again using these numbers as initial estimates. If an actual

minimum has been found, Error 8 will again be displayed and the number

in the X-register will be approximately the same as before, but possibly

closer to the actual location of the minimum.

Of course, you may deliberately use _ to find the location of a local

minimum of the function's magnitude. However, in this case you must be

careful to confine the search in the region of the minimum. Remember,

_ tries hard to find a zero of the function.

If the algorithm stops searching and

displays Error 8 because it is working on a

horizontal asymptote (when the value of

the function is essentially constant for a

large range of x), the estimates in X- and

Y-registers usually are significantly

different from each other. The number in

the Z-register is the value of the potential

asymptote. If you execute _ again

using as initial estimates the numbers that

were returned in the X- and Y-registers, a

horizontal asymptote may again cause Error 8, but with numbers in the X-

and Y-registers that will differ from the previous numbers. The value of the

function in the Z-register would then be about the same as that obtained

previously.

1 2 ... 225 226 227 228 229 230 231 232 233 234 235 ... 287 288

Nessun commento

HP 15C Manuale Utente Pagina 230