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Numerical Differentiation.
Example 1. Find at x = 0.1 from the following table:
Sol. Take a = 0.1. The difference table is:
Here h = 0.1 and y 0 = 0.9975
Example 2. The table given below reveals the velocity ‘v’ of a body during the time ‘t’ specified. Find its acceleration at t = 1.1.
Sol. The difference table is:
Let a = 1.1,
v 0 = 47.7 and h = 0.1
Acceleration at t = 1.1 is given by
Hence the required acceleration is 45.1667.
Example 3. Find f ′ (1.1) and f ″ (1.1) from the following table:
Sol. Since we are to find and
for non-tabular value of x, we proceed as follows:
Newton’s forward difference formula is
(1)
where
(2)
Differentiating eqn. (2) with respect to u, we get
(3)
Differentiating eqn. (2) with respect to x
(4)
Also, at x = 1.1,
The forward difference table is as follows:
From eqn. (4),
(5)
At x = 1.1, we get
Differentiating eqn. (44), with respect to x, we get
At x = 1.1, we get
PROBLEM SET
1. Given that
Find and
at (i) x = 1.1 (ii) x = 1.6.
2. Find first and second derivatives of the function tabulated below at x = 0.6
3. Find y ′(0) and y ″(0) from the given table:
4. Find y ′(1.5) and y ″(1.5) from the following table:
5. Given the following table of values of x and y:
Find and
at (i) x = 1 (ii) x = 1.25 (iii) x = 1.15.
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