19
12
Definite Integrals
(Trapezoidal rule)
Approximations of the value of definite integrals may be obtained as follows:
:number of trapezoids
For larger the approximation improves, and as
tends to infinity it agrees with the precise value of
the definite integral.
Program
?→ A:?→ B:?→ C:1→ D:(√ A)÷2→ Y:Lbl 1:(A(C - D)+ DB)
÷C→X:Y+(√X
)→Y:D+1→D:D≠C⇒Goto 1:Y+(√B)÷2→
Y:(B-A)Y÷C→Y:Y <89 STEP >
INPUT A,B : interval of integration [
A
,
B
] C: number of trapezoids
OUTPUT Y : value of the definite integral
Execution Example:
Calculate the value of the definite integral .
x()xd
A
B
∫
h
2
---
fA() 2fA h+()2fA 2h+()
…
2fB h–()fB()++ +++()≈
h
BA–
n
-------------= n
b
a
nn
ON
MODE MODE MODE
1
PRGM
MODE
1
COMP
1
P1
xxd
0
10
∫
10
20
3
-------------- 21.08185107==
Prog
1
S A
D R
P1
P2 P3 P4
G
0
EXE
S A
D R
P1
P2 P3 P4
G
関数電卓事例集 .book 19 ページ 2002年9月2日 月曜日 午後6時51分