HP 15C Instrukcja Użytkownika Pobierz pdf (Strona 197)

Section 14: Numerical Integration 197

Before calling the subroutine you provide to evaluate f(x), the f

algorithm  just like the _ algorithm  places the value of x in the X-,

Y-, Z-, and T-registers. Because every stack register contains the x-value,

your subroutine can calculate with this number without having to recall it

from a storage register. The subroutines in the next two examples take

advantage of this feature. (A polynomial evaluation technique that assumes

the stack is filled with the value of x is discussed on page 79.)

Note: Since the calculator puts the value of x into all stack

registers, any numbers previously there will be replaced by x.

Therefore, if the stack contains intermediate results that you'll

need after you calculate an integral, store those numbers in

storage registers and recall them later.

Occasionally you may want to use the subroutine that you wrote

for the f operation to merely evaluate the function at some

value of x. If you do so with a function that gets x from the stack

more than once, be sure to fill the stack manually with the value

of x, by pressing vvv, before you execute the

subroutine.

Example: The Bessel function of the first kind of order 1 can be expressed

. )sin - ( cos

)(



 dθθxxJ



Find

. )sin - ( cos

)(



 dθθ1J



Key in the following subroutine that evaluates the function

f(θ) = cos (θ - sin θ).

Keystrokes

Display

| ¥

000-

Program mode.

´ b 1

001-42,21, 1

Begin subroutine with a label.

1 2 ... 192 193 194 195 196 197 198 199 200 201 202 ... 287 288

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HP 15C Instrukcja Użytkownika Strona 197