Paper Code: MATH703
Numerical Analysis
Assignment Task1
Due: 4:00 pm, Thursday 7 May 2020
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Question 1 2 3 4 Total
Fullmark 25 25 25 25 100
Mark
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1. Matlab Fundamentals
(a) [6 points] Use the linspace function to create vectors identical to the following created with colon
notation:
(i) t = 2:5:32
(ii) x = -2:8
(b) [6 points] Use the colon notation to create vectors identical to
(i) v = linspace(-0.5,1.5,5)
(ii) r = linspace(10,5.5,10)
(c) [6 points] The following matrix is entered in Matlab
>> A=[3 2 1;2:0.5:3;linspace(10, 8, 3)]
Write out the resulting matrix. Then, use colon notation to write a single-line MATLAB command
to multiply the first row by the third column and assign the result to the variable C.
(d) [7 points] The standard normal probability density function is given by f(z) = 1
Use Matlab to generate a plot of this function from z = −5 to z = 5. Label the horizontal axis
as z and the vertical axis as frequency.
2. Programming with Matlab
(a) [10 points] The sine function can be evaluated by the following infinite series:
Create an M-file to implement this formula so that it computes and displays the values of sin x as
each term in the series is added. In other words, compute and display in sequence the values for.
up to the order term of your choosing. For each of the preceding, compute and display the percent
relative error as
% error =
true - series approximation
true
× 100%
As a test case, employ the program to compute sin(0.9) for up to and including eight terms, that
is, up to the term x
15/15!. Display the approximation of sin(0.9) and the percent relative error.
(b) [15 points] Two distances are required to specify the location of a point relative to an origin in
two-dimensional space (see figure):
• The horizontal and vertical distances (x, y) in Cartesian coordinates.
• The radius and angle (r, θ) in polar coordinates
It is relatively straightforward to compute Cartesian coordinates (x, y) on the basis of polar
coordinates (r, θ). The reverse process is not so simple. The radius can be computed by the
following formula
If the coordinates lie within the first and fourth coordinates (i.e., x > 0), then a simple formula
can be used to compute
The difficulty arises for the other cases. The following table summarizes the possibilities:
Write a well-structured M-file using if...elseif structures to calculate r and θ as a function of x
and y. Express the coordinates for θ in degrees. Test your program by evaluating the following
cases and finding the values of r and θ:
3. Root finding
(a) [15 points] Use fixed-point iteration to locate the root of
f(x) = cos (√x) − x
Use an initial guess of x0 = 0.5 and iterate until εa ≤ 0.01%. Display graphically the approximate
solutions and relative errors in each iteration steps.
(b) [10 points] Use the Newton-Raphson method to determine a root of
f(x) = −0.9x
2 + 1.6x + 2.6
using x0 = 5. Perform the computation until εa is less than 0.01%.
4. Linear systems
Consider the sixth-degree polynomial y = a0 + a1x + a2x
2 + a3x
3 + a4x
4 + a5x
5 + a6x
6
that passes
through the points (0, 1),(1, 3),(2, 2),(3, 1),(4, 3),(5, 2) and (6, 1).
(a) [10 points] Find a0. Then, set up the system of six equations to find the polynomial coefficients
of a1, a2, ...a6.
(b) [15 points] Wrie a M-file function to solve the system of equations, based on Gauss Elimination
method with pivoting strategy. Use the plot command to display the polynomial and the given
points on the same graph.
2
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