HP 15c - Manual (Page 195)

Section 14: Numerical Integration 195
In Run mode:
2. Key the lower limit of integration (a) into the X-register, then press
v to lift it into the Y-register.
3. Key the upper limit of integration (b) in to the X-register.
4. Press ´ f followed by the label of your subroutine.
Example: Certain problems in physics and engineering require calculating
Bessel functions. The Bessel function of the first kind of order 0 can be
expressed as


π
0
0
) sin ( cos
π
1
) ( dθ
θ
x x J
.
Find


π
0
0
) (sin cos
π
1
(1) dθ
θ
J
.
In Program mode, key in the following subroutine to evaluate the function
f(θ) = cos (sin θ).
Keystrokes Display
|¥ 000–
Program mode.
´ CLEAR M 000–
Clear program memory.
´b 0 001–42,21, 0
Begin subroutine with a
b instruction.
Subroutine assumes a
value of θ is in X-register.
[ 002– 23
Calculate sin θ.
\
003– 24
Calculate cos (sin θ).
|n 004– 43 32
Now, in Run mode key the lower limit of integration into the Y-register and
the upper limit into the X-register. For this particular problem, you also
need to specify Radians mode for the trigonometric functions.