- 2070 Bhadra · 4 marks
y'(1) and y''(1) from table
Short answer
Apply Newton forward differences with h = 0.5 and p = 1. Substituting into the derivative formulas gives y'(1) approximately -3.0667 and y''(1) approximately 7.3333.
Determine y'(1) and y''(1) from the following data.
| x | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 |
|---|---|---|---|---|---|
| y | 6 | 3 | 2 | 1.2 | 0.8 |
The data are equally spaced (h = 0.5), so use Newton's forward-difference formulas with x₀ = 0.5 and p = (x − x₀)/h = (1 − 0.5)/0.5 = 1.
Forward difference table
| x | y | Δy | Δ²y | Δ³y | Δ⁴y |
|---|---|---|---|---|---|
| 0.5 | 6 | -3 | 2 | -1.8 | 2 |
| 1 | 3 | -1 | 0.2 | 0.2 | |
| 1.5 | 2 | -0.8 | 0.4 | ||
| 2 | 1.2 | -0.4 | |||
| 2.5 | 0.8 |
Formulas
y'(x) = (1/h)[Δy₀ + (2p−1)/2·Δ²y₀ + (3p²−6p+2)/6·Δ³y₀ + (4p³−18p²+22p−6)/24·Δ⁴y₀]
y''(x) = (1/h²)[Δ²y₀ + (p−1)Δ³y₀ + (6p²−18p+11)/12·Δ⁴y₀]
Substitute p = 1
y'(1) = (1/0.5)[ -3 + (1/2)(2) + (−1/6)(-1.8) + (2/24)(2.0) ]
= 2[ -3 + 1.0000 + 0.3000 + 0.1667 ]
= -3.0667
y''(1) = (1/0.25)[ 2 + 0·(-1.8) + (−1/12)(2.0) ]
= 4[ 2 − 0.1667 ]
= 7.3333
Answer: y'(1) ≈ -3.0667, y''(1) ≈ 7.3333
Check with the 3-point central formulas (less accurate for this coarse table): y'(1) = (2−6)/(2×0.5) = -4.0000, y''(1) = (2 − 6 + 6)/0.25 = 8.0000.
✓ Answer checked by Claude Opus 5.5 (high effort)
Related questions
- Difference table (3.0 to 3.8) · Numerical Method, chapter 4
- Newton interpolation: steam table · Numerical Method, chapter 4
- Forward difference table · Numerical Method, chapter 4
- Angular velocity from rod data · Numerical Method, chapter 5 · asked 2×
- Linear probing insertion into size-10 table · Data Structure and Algorithm, chapter 8
- Hash table with chaining, m = 13 · Data Structure and Algorithm, chapter 8
- Double hashing table with m = 11 · Data Structure and Algorithm, chapter 8
- ANOVA table: wheat varieties on four plots · Probability and Statistics, chapter 6