How to edit the red "+" marks on the Nyquist plot

Regarding the line of code you asked about, before that line is executed, h contains all the line objects in the figure. That line of code compares the marker of each line object to '+' and keeps only the line objects whose marker is '+', so that afterwards h contains only those line objects whose marker is '+'.

Steven Lord 2024-7-9，14:04

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A slightly simpler approach would be to directly findobj all objects whose Marker property is '+'.

H = tf([2 5 1],[1 2 3]);

nyquist(H)

h = findall(gcf(),'Marker', '+')

h =

Line with properties: Color: [1 0 0] LineStyle: '-' LineWidth: 0.5000 Marker: '+' MarkerSize: 6 MarkerFaceColor: 'none' XData: -1 YData: 0 ZData: -10 Use GET to show all properties

The properties (specifically Color, Marker, XData, and YData) indicate that this is the "line" that is the red + symbol. This avoids the strcmp call.

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Answer 2

Umar 2024-7-5，12:01

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https://ww2.mathworks.cn/matlabcentral/answers/2134706-how-to-edit-the-red-marks-on-the-nyquist-plot#answer_1481706

Hi Ayumi,

To change the thickness and color of the red + marks in a Nyquist diagram, you can modify the properties of the plot after generating it. Below is an example illustrating how to achieve this customization. So, first, I will create a transfer function G as an example.Next, generate the Nyquist plot using the nyquist function. Afterwards, access the current figure handle and find all lines with a red color (indicating the + marks). Finally, we set the line width to 2 and change the color to blue for better visibility.

>> % Create a transfer function G = tf([1], [1, 2, 1]);

% Generate the Nyquist plot figure; nyquist(G);

% Access the current figure and set properties of the red + marks h = gcf; % Get current figure handle redPlusMarks = findall(h, 'Type', 'line', 'Color', [1 0 0]); % Find red lines set(redPlusMarks, 'LineWidth', 2); % Set line width to 2 set(redPlusMarks, 'Color', [0 0 1]); % Set color to blue

Please see attached plot as reference.

By following this approach, you can easily customize the appearance of the red + marks in Nyquist diagrams according to your preferences.