![02/02/2025
Arithmetic with Random Arrays
1. If elements in an array are NOT evenly-spaced out, then you DO have to type out all of them.
2. X= [0, 4, 3, 6], defines a one-dimensional array with 4 elements.
3. Y = [1, 2, 3, 0] another one-dimensional array
4. X+Y = [1, 6, 6, 6] (adding 2 arrays)](https://image.slidesharecdn.com/eet-1102lecture2-250202023144-f3e372a7/85/EET-Lecture-for-matlab-khjbxiubnxjnkjnw-17-320.jpg)
![02/02/2025
Solving for Roots
To find the roots of x^3 – 7x^2 + 40x – 34 = 0, the session is
>>a = [1,-7,40,-34];
>>roots(a)
ans =
3.0000 + 5.000i
3.0000 - 5.000i
1.0000
The roots are x = 1 and x = 3 ± 5i.](https://image.slidesharecdn.com/eet-1102lecture2-250202023144-f3e372a7/85/EET-Lecture-for-matlab-khjbxiubnxjnkjnw-18-320.jpg)
![02/02/2025
System of Equations
6x + 12y + 4z = 70
7x – 2y + 3z = 5
2x + 8y – 9z = 64
>>A = [6,12,4;7,-2,3;2,8,-9];
>>B = [70;5;64];
>>Solution = AB
Solution =
3
5
-2
The solution is x = 3, y = 5, and z = –2.
Use ‘;’ to separate rows in a MATRIX.](https://image.slidesharecdn.com/eet-1102lecture2-250202023144-f3e372a7/85/EET-Lecture-for-matlab-khjbxiubnxjnkjnw-29-320.jpg)
![02/02/2025
Magnitude, Length, and Absolute Value
of a Vector
X=[2,-4,5];
The length command gives the number of elements in the vector. length(x)
The magnitude of a vector x having elements x1, x2, …, xn is a scalar, given by
sqrt(x1
2
+ x2
2
+ … + xn
2
), and is the same as the vector's geometric length (recall
Pythagorean theorem A^2+B^2=C^2 where C is the magnitude of the vector).
Use the norm(x) command.
The absolute value of a vector x is a vector whose elements are the absolute
values of the elements of x. Use the abs(x) command.](https://image.slidesharecdn.com/eet-1102lecture2-250202023144-f3e372a7/85/EET-Lecture-for-matlab-khjbxiubnxjnkjnw-34-320.jpg)
EET Lecture for matlab khjbxiubnxjnkjnw
- 1. 02/02/2025 EET 1102-Techniques of Electrical Technology LECTURE 2: MATLAB PART 1 PROF. ABDULLAH HOSSAIN NEW YORK CITY COLLEGE OF TECHNOLOGY
- 2. 02/02/2025 Outline (not necessarily sequential) 1. MATLAB interface 2. Arrays, Vectors, Matrices 3. Arithmetic Operations, Order of Operations, Control Commands 4. Plotting 5. System of Equations 6. Commenting 7. Script Files, Saving Variables
- 3. 02/02/2025
- 4. 02/02/2025 Entering Commands and Expressions 1. MATLAB retains your previous keystrokes. 2. Use the up-arrow key to scroll back through the commands. 3. Press the key once to see the previous entry, and so on. 4. Use the down-arrow key to scroll forward. 5. Press the Enter key to execute the command.
- 9. 02/02/2025 Does the Variable Exist?
- 11. 02/02/2025 Special variables and constants
- 12. 02/02/2025 Complex Numbers 1. The number c1 = 1 – 2i is entered as follows: c1 = 1 -2i. 2. An asterisk is not needed between i or j and a number, although it is required with a variable, such as c2 = 5 - i*c1. 3. The expressions y = 7/2*i and x = 7/2i give two different results. 4. y = (7/2)i = 3.5i and x = 7/(2i) = –3.5i
- 13. 02/02/2025 Numeric display formats >> format long %16 digits accuracy >> 1/3 ans = 0.333333333333333
- 14. 02/02/2025 Variable Types Variable Description char Character array complex Complex data. Cast function takes real and imaginary components double Double-precision floating point (64 bits long, range for negative numbers is -1.79769 x 10^308 to -2.22507 x 10- 308, for positive numbers is 2.22507 x 10^-308 to 1.79769 x 10^308 int8, int16, int32, int64 Signed integer logical Boolean true or false single Single-precision floating point (32 bits long) struct Structure uint8, uint16, uint32, uint64 Unsigned integer Fixed-point Fixed-point data types
- 15. 02/02/2025 Arrays 1. If elements in an array are evenly-spaced out, then you don’t have to type all of them. 2. Format to generate an array: 1. List_name= StartingpointofList: Stepsize : EndingpointofList 3. The numbers 0, 0.1, 0.2, …, 10 can be assigned to the variable u by typing u = 0:0.1:10. 4. To compute w = 5 sin u, for u = 0, 0.1, 0.2, …, 10, the session is; u = 0:0.1:10; w = 5*sin(u); 3. The single line, w = 5*sin(u), computed the formula w = 5 sin u, a 101 times.
- 16. 02/02/2025 Array Index (nth item of an array) >>u(7) ans = 0.6000 >>w(7) ans = 2.8232 Use the length function to determine how many values are in an array. >>length(w) ans = 101
- 17. 02/02/2025 Arithmetic with Random Arrays 1. If elements in an array are NOT evenly-spaced out, then you DO have to type out all of them. 2. X= [0, 4, 3, 6], defines a one-dimensional array with 4 elements. 3. Y = [1, 2, 3, 0] another one-dimensional array 4. X+Y = [1, 6, 6, 6] (adding 2 arrays)
- 18. 02/02/2025 Solving for Roots To find the roots of x^3 – 7x^2 + 40x – 34 = 0, the session is >>a = [1,-7,40,-34]; >>roots(a) ans = 3.0000 + 5.000i 3.0000 - 5.000i 1.0000 The roots are x = 1 and x = 3 ± 5i.
- 23. 02/02/2025 Multiple Plots with Overlaid Text Plot the following functions on the same plot: Answer: >>x = 0:0.01:5; %(0, 0.01, 0.02, 0.03,0.04,…5) >>y=2*sqrt(x); >>z=4*sin(3*x); >>plot(x,y,x,z), xlabel(‘x’), gtext(‘y’), gtext(‘z’), legend (‘square root’,’sin') After the plot appears on the screen, the program waits for you to position the cursor and click the mouse button, once for each gtext function used.
- 24. 02/02/2025 Plotting with different line types Using different line types for each curve For previous example change plot(x,y,x,z) to plot(x,y,x,z, ‘ - -’), and it will plot the z-curve with a dashed line.
- 29. 02/02/2025 System of Equations 6x + 12y + 4z = 70 7x – 2y + 3z = 5 2x + 8y – 9z = 64 >>A = [6,12,4;7,-2,3;2,8,-9]; >>B = [70;5;64]; >>Solution = AB Solution = 3 5 -2 The solution is x = 3, y = 5, and z = –2. Use ‘;’ to separate rows in a MATRIX.
- 30. 02/02/2025 Comments The comment symbol may be put anywhere in the line. MATLAB ignores everything to the right of the % symbol. For example, >>% “This is a comment. This is ignored by MATLAB.” >>x = 2+3 % Question 1 of Assignment x = 5 Note that the portion of the line before the % sign is executed to compute x.
- 31. 02/02/2025 Prompting User for Numerical/Text Input
- 32. 02/02/2025 Script Files 1. Running a MATLAB program stored in script file is equivalent to typing all the commands at once and executing them. 2. Script files can be sent to other users so that it can be run on their MATLAB easily. 3. You can make further edits to the code in the script later on. 4. The name of a script file must begin with a letter, may include digits and the underscore character, and can be up to 63 characters. Do not use space. 5. Do not give a script file the same name as a variable. 6. Do not give a script file the same name as a MATLAB command or function.
- 33. 02/02/2025 Linspace 1. The linspace command also creates an evenly spaced-out row vector but you specify the number of values rather than the increment. 2. The syntax is linspace(a,b,n), where a and b are the lower and upper limits and n is the number of points; inclusive of the bounds. 3. linspace(5,8,31) means I generate 31 points, including 5 and 8, which are evenly spaced out. 4. The increment can be determined by: (b-a)/(n-1).
- 34. 02/02/2025 Magnitude, Length, and Absolute Value of a Vector X=[2,-4,5]; The length command gives the number of elements in the vector. length(x) The magnitude of a vector x having elements x1, x2, …, xn is a scalar, given by sqrt(x1 2 + x2 2 + … + xn 2 ), and is the same as the vector's geometric length (recall Pythagorean theorem A^2+B^2=C^2 where C is the magnitude of the vector). Use the norm(x) command. The absolute value of a vector x is a vector whose elements are the absolute values of the elements of x. Use the abs(x) command.