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Num. Factor mode
When the Num. Factor setting is selected, approximate roots are used when factoring. For example,
is irreducible over the integers but has approximate roots over the reals. With Num. Factor set, the
approximate roots are returned. [Default: unselected]
Comment:
Some polynomials, particularly ones with complex coefficients, will not factorize using the
FACTOR
function without being in Num. Factor mode. See the example on page 346.
Complex vs. Real mode
When Complex mode is selected and an operation results in a complex number, the result will be
shown in the form a + bi or in the form of an ordered pair (a,b). If Complex mode is not selected and
an operation results in a complex number, you will be asked to switch to Complex mode. If you
decline, the calculator will report an error or, in the case of factorizing, simply return the original
expression. [Default: unselected.]
When in Complex mode, the CAS is able to perform a wider range of operations than in non-
complex (or real) mode, but it will also be considerably slower. Thus, it is recommended that you
don’t select Complex mode unless requested by the calculator in the performance of a particular
operation.
Comment:
That says it all really. You need to be concerned with this if you are finding roots of
polynomials. If Complex mode is not selected then only the real roots will be returned.
Verbose vs. nonverbose mode
When verbose mode is selected, certain calculus applications are provided with comment lines in the
main display. The comment lines will appear in the top lines of the display, but only while the
operation is being calculated. [Default: unselected.]
Comment:
I’ve never found the comments to be particularly helpful. The methodology and algorithms that
the CAS uses internally are not those that normal mathematicians use in many cases and so
Verbose mode gives little useful information.
Step-by-step mode
When Step/Step is selected, certain operations will be shown one step at a time in the display. You
press to show each step in turn. [Default: selected.]
Comment:
This can be useful for functions such as
INTVX
and
LINSOLVE
(see earlier examples) where
they give important information on how the problem was solved.
Try
INTVX(SIN(X)
2
/COS(X))
for an illustration. The information is stored in the
VARS
screen
in the
CASINFO
variable and can be viewed again there if desired.
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