# 2. Notes

## 2.1. Plotting array elements

 In MATLAB, line plots are created using the plot function. % Create an array to plot A = [1.0,4.0,16.0,32.0]; clf; % Clear the plot window plot(A)  From raw.githubusercontent.com on May 19 2019 09:24:15.
 The plot(A) command caused a plot of the values of A to be shown with the values in A shown on the y-axis. The x-axis values were assumed to be [1,2,3,4]. The above commands are equivalent to A = [1.0,4.0,16.0,32.0]; x = [1,2,3,4]; clf; % Clear the plot. plot(x,A);  From raw.githubusercontent.com on May 19 2019 09:24:15.
 To change the x-axis values, modify the first array that is passed to the plot function. A = [1.0,4.0,16.0,32.0]; x = [10,20,30,40]; clf; % Clear the plot window plot(x,A);  From raw.githubusercontent.com on May 19 2019 09:24:15.

## 2.2. Annotation

 To add a grid, write grid on after the plot command. To add a axis labels and a title, use xlabel, ylabel, and title A = [1.0,4.0,16.0,32.0]; x = [1,2,3,4]; clf; plot(x,A); grid on; xlabel('Time [seconds]'); ylabel('Height [meters]'); title('Experiment 1 results');  From raw.githubusercontent.com on May 19 2019 09:24:15.

## 2.3. Line Color

 A style argument may be specified when calling the plot function. This set of commands will create a red line. clf; A = [1.0,4.0,16.0,32.0]; x = [1,2,3,4]; % Can be one of r,g,b,c,m,y,k,w style = 'r'; plot(x,A,style);  From raw.githubusercontent.com on May 19 2019 09:24:15.
 Other colors may be used by specifying a set of r,g,b values. This set of commands will create a gray line. clf; A = [1.0,4.0,16.0,32.0]; x = [1,2,3,4]; plot(x,A,'Color',[0.5,0.5,0.5]);  From raw.githubusercontent.com on May 19 2019 09:24:15.

## 2.4. Marker Style

 Marker styles are one of .,o,x,+,*,s,d,v,^,<,>,p,h A = [1.0,4.0,16.0,64.0]; x = [1,2,3,4]; % Can be one of % .,o,x,+,*,s,d,v,^,<,>,p,h style = '*'; clf; plot(x,A,style);  From raw.githubusercontent.com on May 19 2019 09:24:15.

## 2.5. Axis Numbering

In this example, note that by default MATLAB chose to label the values in 0.5 increments. This is not a good default - all of the x-values are integers. The following example shows how to modify the values that are labeled.

 To modify the x-position labels, use YTick instead of XTick. A = [1.0,4.0,16.0,32.0]; x = [1,2,3,4]; clf; plot(x,A); % Label x-position labels % at 1, 2, 3, and 4. set(gca,'XTick',[1:4]); grid on; xlabel('Time [seconds]'); ylabel('Height [meters]'); title('Experiment 1 results');  From raw.githubusercontent.com on May 19 2019 09:24:15.

# 3. Problems

## 3.1. Scalar Time Series Plots I

Create a the plot shown below. The plot must have a grid, labels, x symbols of size 20, and a green line of width 3.

Turn in your program and a print-out of the plot (you can print both the program and the plot from within MATLAB using File-Print.)

## 3.2. Scalar Time Series Plots II

The following program computes population for two different scenarios.

• An initial population of 100 and a growth rate of 1%/yr.
• An initial population of 1000 and a decay rate of 10%/yr.
Pa(1) = 100;
for i = 2:40
Pa(i) = Pa(i-1) + 0.05*Pa(i-1);
end

Pb(1) = 1000;
for i = 2:40
Pb(i) = Pb(i-1) - 0.10*Pb(i-1);
end


Plot both population scenarios and draw a vertical line at the year in which the populations are nearest each other.

The plot should contain a legend and axis labels on the plot.