5 Numerical Differentiation

Numerical Methods · Unit 5

Numerical Differentiation

Exam-focused notes for Numerical Differentiation (Numerical Methods, BIT203): what the TU syllabus asks and how it has actually been tested, with 4 solved past questions from this unit.

What this unit covers

  • Derivatives of continuous functions
  • Two point forward difference formula
  • Two point backward difference formula
  • Divided difference table for derivatives
  • First and second order derivatives
  • Algorithm and program for numerical differentiation

Two point forward difference formula

20825 marks

Derive the formula for two points forward difference. Derive the formula for two points backward difference. [2.5+2.5]

Note: The reference notes were not available for this topic. The derivation below follows the standard numerical methods approach as taught in BSc CSIT curriculum. --- (a) Two-Point Forward Difference Formula The forward difference formula approximates the ...

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Divided difference table for derivatives

20825 marks

Find the first and second derivative at $x = 2.5$ of the following data points.

$$\begin{array}{|c|cccccc|}\hline x & 1.5 & 2 & 2.5 & 3 & 3.5 & 4 \ \hline f(x) & 2.375 & 4.5 & 7.625 & 12 & 17.875 & 23 \ \hline \end{array}$$

[5]

$x$ 1.5 2.0 2.5 3.0 3.5 4.0 ----------------------------------- $f(x)$ 2.375 4.5 7.625 12 17.875 23 - Step size: $h = 0.5$ - Point of interest: $x = 2.5$ Take $x0 = 2.5$ so that $p = 0$. First compute all differences carefully. $x$ $f$ $\Delta f$ $\Delta^2 ...

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20785 marks

The table below gives the values of distance travelled by a car at various time intervals during the initial running. Estimate the velocity and acceleration at time t = 7 sec.

$$\begin{array}{|c|c|c|c|c|c|}\hline \text{Time (t sec)} & 5 & 6 & 7 & 8 & 9 \ \hline \text{Distance (s m)} & 10.0 & 14.5 & 19.5 & 25.5 & 32.0 \ \hline \end{array}$$

[5]

Time $t$ (sec) 5 6 7 8 9 ------------------ Distance $s$ 10.0 14.5 19.5 25.5 32.0 - Uniform spacing $h = 1$ - Required: velocity $\frac{ds}{dt}$ and acceleration $\frac{d^2s}{dt^2}$ at $t = 7$ (The problem header mislabels the second row as "Temp"; from con...

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Algorithm and program for numerical differentiation

05 marks

How can we calculate derivatives of continuous functions? Write down algorithm and program for differentiating continuous function using two point forward difference formula. [5]

For a continuous function f(x), the derivative at a point x is defined as: $$f'(x) = \lim{h \to 0} \frac{f(x+h) - f(x)}{h}$$ In numerical methods, we cannot take the limit analytically for arbitrary functions, so we approximate the derivative by choosing a ...

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