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above. Their result is the so-called discrete derivative, i.e., one defined for
integer numbers only.
Definite integrals
In a definite integral of a function, the resulting anti-derivative is evaluated at the
upper and lower limit of an interval (a,b) and the evaluated values subtracted.
Symbolically, where f(x) = dF/dx.
The PREVAL(f(x),a,b) function of the CAS can simplify such calculation by
returning f(b)-f(a) with x being the CAS variable VX.
To calculate definite integrals the calculator also provides the integral symbol as
the keystroke combination ‚Á (associated with the U key). The simplest
way to build an integral is by using the Equation Writer (see Chapter 2 for an
example). Within the Equation Writer, the symbol ‚Á produces the
integral sign and provides placeholders for the integration limits (a,b), for the
function, f(x), and for the variable of integration (x). The following screen shots
show how to build a particular integral. The insert cursor is first located in the
lower limit of integration, enter a value and press the right-arrow key (™) to
move to the upper limit of integration. Enter a value in that location and press
™ again to move to the integrand location. Type the integrand expression,
and press once more to move to the differential place holder, type the variable
of integration in that location and the integral is ready to be calculated.
At this point, you can press ` to return the integral to the stack, which will
show the following entry (ALG mode shown):
),()()( aFbFdxxf
b
a
−=
∫