HP 33s - Manual (Page 332)

D–8 More about Solving
Now, solve to find the root.
Keys: Display: Description:
2.3 I X
2.7

)
_ Your initial guesses for the
root.
| H
%ª1%:. 2. Selects Equation mode;
displays the equation.
 X   ! No root found for f(x).
8  8  8
)
f(x) is relatively large.
When SOLVE Cannot Find a Root
Sometimes SOLVE fails to find a root. The following conditions cause the message
 ! :
„ The search terminates near a local minimum or maximum (see figure a,
below). If the ending value of f(x) (stored in the Z–register) is relatively close
to zero, it is possible that a root has been found; the number stored in the
unknown variable might be a 12–digit number very close to a theoretical
root.
„ The search halts because SOLVE is working on a horizontal asymptote—an
area where f(x) is essentially constant for a wide range of x (see figure b,
below). The ending value of f(x) is the value of the potential asymptote.
„ The search is concentrated in a local "flat" region of the function (see figure c,
below). The ending value of f(x) is the value of the function in this region.