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Matlab Functions


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Matlab Functions and types

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Matlab Functions

  1. 1. 13033386-018 Umar Azeem University of Gujrat
  2. 2. A function is a MATLAB program that can accept inputs and produce outputs A function is a group of statements that together perform a task. Functions can accept more than one input arguments and may return more than one output arguments
  3. 3. Functions provide reusable code Use same code in more than one place in program without rewriting code Reuse code by calling in different programs
  4. 4. Built in Function User define Function
  5. 5. Built in Function
  6. 6. + Plus; addition operator. - Minus; subtraction operator. * Scalar and matrix multiplication operator. .* Array multiplication operator. ^ Scalar and matrix exponentiation operator. .^ Array exponentiation operator.  Left-division operator. / Right-division operator. . Array left-division operator. ./ Array right-division operator.
  7. 7.  : Colon; generates regularly spaced elements and represents an entire row or column.  ( ) Parentheses; encloses function arguments and array indices; overrides precedence.  [ ] Brackets; enclosures array elements.  ., Comma; separates statements and elements in a row.  ; Semicolon; separates columns and suppresses display.  % Percent sign; designates a comment and specifies formatting.  = Assignment (replacement) operator.
  8. 8. clc -Clears Command window. Clear- Removes variables from memory. exist -Checks for existence of file or variable. Global- Declares variables to be global. help -Searches for a help topic. Lookfor- Searches help entries for a keyword. quit -Stops MATLAB. who -Lists current variables. whos -Lists current variables (long display).
  9. 9. Cd-Changes current directory. Date-Displays current date. Delete-Deletes a file. Diary-Switches on/off diary file recording. dir-Lists all files in current directory. Load-Loads workspace variables from a file. Path-Displays search path. Save-Saves workspace variables in a file.
  10. 10. max(x) min(x) mean(x) median(x) sum(x)
  11. 11. sin(x) sine cos(x) cosine tan(x) tangent asin(x) inverse sine sinh(x) hyperbolic sine asinh(x) inverse hyperbolic sine sind(x) sine with degree input asind(x) inverse sin with degree output
  12. 12. User define Function
  13. 13. Identify the function Decide the function name Decide the input variables Decide the output variables File name must be the function name.
  14. 14. function[a, b, c]= basicmath(x,y) %BASICMATH Basic Mathematical function % basicmath(x,y) is a sample matlab function to perform % basic mathematical operations on input variables x & y % outputs of the function are sum, difference and product of input arguments. a = x + y; b = x – y; c = x * y; 14 Output arguments Executable code Comments about the function Name of the function Input arguments declaration statement
  15. 15. The declaration statement function is used to define the file as a function. It must be typed in lower case letters. Input arguments • Can be zero or more input arguments. Output arguments • Types inside the square brackets [ ] Give a meaningful variable name.
  16. 16. • The function have only one out put you don’t need to put it inside the square brackets [ ]  Example:  The function in a file named average.m that accepts an input vector, calculates the average of the values, and returns a single result. function y = average(x) y = sum(x)/length(x); end
  17. 17. When there are more than one output arguments put them in a square bracket. Example function[a, b, c]= basicmath(x,y) a = x + y; b = x – y; c = x * y;
  18. 18.  A function can be called from the command window or inside a script or function.  To run a function in command window, just type the name of comment with proper input and output arguments • For example consider the function basicmath >> [a,b,c] = basicmath (2,3) a = 5 b = -1 c = 6
  19. 19. Function name and file name must be same. Unlike other programming languages, Function in MATLAB can return more than one value. Syntax: function outputs=function_name(inputs)  There is no starting and ending curly braceS to enclose the body of function, instead, there is an end statement which signifies end of function.
  20. 20. To run a function we type a function name with valid arguments in command window area. If function returns two or more ouputs,to see all the outputs, we must not put semicolon after the output statement. Note: if we put semicolon, we will see only the first output.
  21. 21. MATLAB contains a wide array of predefined functions •Elementary Math Functions •Trigonometric Functions •Data Analysis Functions •Random Numbers •Complex Numbers
  22. 22. Thank You