198 Section 14: Numerical Integration

 

Keystrokes

Display

 

 

[

002–

23

Calculate sin θ.

-

003–

30

Since a value of θ will be

 

 

 

placed into the Y-register by

 

 

 

the falgorithm before it

 

 

 

executes this subroutine, the

 

 

 

-operation at this point

 

 

 

will calculate

 

 

 

(θ – sin θ).

\

004–

24

Calculate cos (θ sin θ).

n

005–

43 32

 

In Run mode, key the limits of integration into the X- and Y-registers. Be sure that the trigonometric mode is set to Radians, then press ´f1 to calculate the integral. Finally, multiply the integral by 1/π to calculate J1 (1).

Keystrokes

Display

 

¥

 

Run mode.

0 v

0.0000

Key lower limit into

 

 

Y-register.

$

3.1416

Key upper limit into

 

 

X-register.

R

3.1416

(If not already in

 

 

Radians mode.)

´f1

1.3825

 

0.4401

J1 (1).

Example: Certain problems in communications theory (for example, pulse transmission through idealized networks) require calculating an integral (sometimes called the sine integral) of the form

Si(t) = 0t sin(x x) dx .