CSCI291 Programming for Engineers UOW
Laboratory Exercises - Week 4
Topics:
- User defined data types
- User defined functions
1. Create a sub-folder lab4 inside your CSCI291 folder.
2. Write a prototype and a definition of the function iirFilter() that implements a
low-pass digital IIR filter used for noise reduction of corrupted signals
A simple low-pass IIR filter produces an output sample that is an average of an input
sample and of the filter output from the previous time interval. For example:
Input: 0 10 15 10 12 14
Output: 5 10 10 11 12.5
(10+0)/2 = 5
(15 +5)/2 = 10
(10 + 10)/2 = 10
(12 + 10)/2 = 11
The function shall take one parameter of type float and return value of type float.
/* -- function prototype-- */
float iirFilter( float input );
A hint: You can use a static variable to keep the previous output sample
Test the function to make sure it works according to the requirements.
Implement a top level function that calls iirFilter() to filter an array of signal samples.
/* -- function prototype-- */
void suppressNoise( const float inData[ ], float outData[ ], int signalLength );
Test the function to make sure it works according to the requirements.
IIR
Input
(with noise)
Output
(noise filtered out)
CSCI291 Programming for Engineers UOW
Implement the main() function that declares an array of 12 float values (initialized at
the time of declaration) and uses supressNoise() to filter them and store the result
in an array of filtered samples. The result of filtering shall be displayed with the 1-
decimal point precision.
3. Radio signals are described by complex numbers. As a result, all digital signal
processors have to support operations on complex numbers. Each complex number is
comprised of two parts: Real and Imaginary. Define a function getModulus(), that
calculates the module of a complex number according to the formula
modulus = (real2
+ imaginary2
)
1/2
The function shall take a parameter of struct type complexnumber that represents
the real part and the imaginary part of a number. The function shall return a value of type
float equal to the modulus of that complex number. To raise numbers to power of 2
and calculate a square root you can use standard function pow(x,y) and sqrt(x)
from math.h library.
float getModulus( compnumber number );
Implement the main() function that calls getModulus() to calculate modules of
three different complex numbers.
4. Implement a program that performs basic 2D geometrical transformations on points in
a 2D coordinate space.
The coordinate can be defined as a structure
typedef struct
{
float x;
float y;
}coordinate;
A point in 2D coordinate space can now be declared as a variable
Example:
coordinate pointA = { 1.0, 2.5};
Transformations to be implemented as three functions:
1. Horizontal shift:
xNew = xOriginal + horisontalOffset
2. Vertical shift:
yNew = yOriginal + verticalOffset
3. Rotation (about the origin)
xNew = cos(angle)*xOriginal + sin(angle)*yOriginal;
yNew = -sin(angle)*xOriginal + cos(angle)*yOriginal;
CSCI291 Programming for Engineers UOW
Test the functions with two different points.
Implement the main() function that
- declares a variable triangle (its type shall be defined as a nested struct with
three nodes of type coordinate)
- uses functions for three basic transformations on triangles. As you declare a new data
type for triangles, you may need to define a set of new functions, which will utilize
the low level functions defined earlier for coordinates in order to manipulate
triangles (shift horizontally, shift vertically and rotate).
- Your main program should accept data in the following format:
P0 x y (set first triangle point)
P1 x y (set second triangle point)
P2 x y (set third triangle point)
T x y (translate the triangle by x horizontally and y vertically)
R d (rotate the triangle about the origin by d degrees)
O (output the current coordinates of the triangle)
Q (quit the program)
- An example run might look like this:
Output will appear here
Q
Zip all source and header files and submit to the lab3 area on Moodle.
Summary of UNIX / Linux commands
ls list files and directories
rm file remove a file
mkdir name
rm –rf name
make a directory
remove a directory
cp source destination copy files between directories
cd directory change to named directory
cd ~ change to home-directory
cd .. change to parent directory (one level up )
pwd display the path of the current directory
CSCI291 Programming for Engineers UOW
GNU gcc compilation options
$ gcc options file.c
You may not specify any option. In this case an executable a.out will be produced. Your program will not
be checked for ANSI standard compliance, some specious operations will not be reported, the code is not
optimized.
options
-o name Produce an executable with the specified name
-ansi Verify if the source code is compliant with ANSI/ISO standard
-Wall Report all warnings
To see complete list of options see gcc manual pages: $ man gcc