You can have MATLAB compute the values at and 0. You can check that this is right except at the and at 0 by plotting. Heaviside(2 - x)*heaviside(x) - heaviside(-x)*heaviside(x + 2) Exampleĭefine a symbolic MATLAB function which is equal to if and is equal to if This is Boyce and DiPrima, Section 10.2 #19.į = -heaviside(x+2)*heaviside(-x)+heaviside(x)*heaviside(2-x) The unit step function is known to MATLAB as heaviside, with the slight difference that heaviside(0)=1/2. Then is 1 where and, so on the interval, and and it is 0 outside the interval. Also, for plotting purposes, there is no need to evaluate the equation of a line over several discrete points. This is the function in Section 6.3 of Boyce and DiPrima. To implement the above function in Matlab first we need to create one function with keyword ‘ piecewise ’. Use the unit step function or Heaviside function to define the piecewise function. The MATLAB provides a built-in function “piecewise” which takes the equations and conditions as an argument and returns a piecewise expression.Suppose is equal to on the interval and on the interval and you want to define it as a MATLAB function. # Plotting Piecewise function using switch case statements If the ‘case’ condition is true, then that means x lies in the interval specified by that case expression and the appropriate statements will be executed. First of all, the case expressions check the value of x. A piecewise function with a discrete point can be plotted by plotting the components of the piecewise function as demonstrated above and plotting the discrete. We have separated the intervals of different sub-functions in different cases. It is almost similar to the above method but in this case, we have replaced the if-else with switch-case statements. Output: Figure 3 using switch-case statements The plot(x, result) command plots the values in variable “result” against ‘x’. The values calculated are stored into an array ‘result’ which represents the piecewise function values with respect to input (x). In this case, the body of the if statement consists of only one statement which is ” result = x.^2 “. As the value of x lies in the (0,2] interval, therefore, the x will enter into the body of the 2nd elseif condition. Here, if-else conditions are used to check the interval where the input(x) lies. The “piecewise_function” takes the value and check the conditions of if-else statements. Then, we have used a for loop which iterates over an array x and passes these values to the “piecewise_function”. The array x specifies the range of values on which we want to obtain the results of the piecewise function. We can also use “linspace” command to create an array. In this code, we have created an array “x” by using the colon operator. % create a function to plot piecewise function %iterate over the elements in x one-by-one and calculate the value of f(x) % Plotting piecewise function using if else statements. In this method, we’ll define all the sub-functions along with the constraints using if-else statements and then we will plot the piecewise function. The second method involves the use of if-else statements along with for loop. Output: Figure 2 using if-else statements The graph in fig 2 shows the output obtained as a result of the plot(x, y) command. The plot(x, y) command then plots y against x. Then, we have created an array using all the intervals i.e., ‘x’ and an array of ‘y’ representing the different equation values. In the code given above, eq1, eq2, and eq3 represent the three equations whereas x1, x2, and x3 define the intervals for their respective equations.
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