How do I take a normal script with a function and turn it into a script with an anonymus function?

Question

Mark Dillon 2015-7-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/230652-how-do-i-take-a-normal-script-with-a-function-and-turn-it-into-a-script-with-an-anonymus-function

评论： Star Strider 2015-7-22

I am trying to use this old script I wrote and turn it into an anonymous function script using a loop. I am having some issues though, and I think I have just not refined ever variable and function to operate the way I need it to.

Here is the script I have worked on so far to change to anonymous:

if true
  % 
  % Clear Window, Variables, and Figure
  clear;
  clc;
  clf;
    % Variables
    time_interval = 0.04; % seconds
    tVals = (-5:time_interval:1);  % -5 to 1 in steps of 0.04
    % Equation
    y = @(t) t.^2+3.*t+4;
    % Making a for loop
    for k = 1:length(tVals)
        yVals = y(tVals(k)); % t will take on the values of tVals
        % Plot the result
        plot(tVals(k),yVals,'-r'); % Plots t-values vs y-values; in default color (blue)
        % Label the Graph
        xlabel('Time (seconds)'); % Labels x-axis
        ylabel('Distance (meters)'); % Labels y-axis
        title('Time vs. Distance'); % Titles the graph
    end
        % Find min/max value of y and time when it occurs
        [ymax, t1] = max(yVals);
        [ymin, t2] = min(yVals);
        % Print Part a
        fprintf('The max value of y is %.2f meters and occurs at t=%.1f seconds \n', ymax, tVals(t1));
        fprintf('The min value of y is %.2f meters and occurs at t=%.1f seconds \n', ymin, tVals(t2));
  end

And here is the old script:

if true
  %    
  % Clear Window, Variables, and Figure
  clear;
  clc;
  clf;
    % Variables
    time_interval = 0.04; % seconds
    t = [-5:time_interval:1];  % -5 to 1 in steps of 0.04
    % Equation
    y = t.^2+3.*t+4;
    % Plot the result
    plot(t,y); % Plots t-values vs y-values; in default color (blue)
    % Label the Graph
    xlabel('Time (seconds)'); % Labels x-axis
    ylabel('Distance (meters)'); % Labels y-axis
    title('Time vs. Distance'); % Titles the graph
    % Find min/max value of y and time when it occurs
    [ymax, t1] = max(y);
    [ymin, t2] = min(y);
    % Print Part a
    fprintf('The max value of y is %.2f meters and occurs at t=%.1f seconds \n', ymax, t(t1));
    fprintf('The min value of y is %.2f meters and occurs at t=%.1f seconds \n', ymin, t(t2));
  end

The old function returns fine giving me the proper plot and min and max values, but the new script does not bring up the plot and returns the min and max values as the same numbers.

Any advice or help would be greatly appreciated.

Thank you.

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Answer 1

Star Strider 2015-7-21

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/230652-how-do-i-take-a-normal-script-with-a-function-and-turn-it-into-a-script-with-an-anonymus-function#answer_186795

在 MATLAB Online 中打开

You can take advantage of vectorisation and your anonymous function to do it without a loop:

% Variables
time_interval = 0.04; % seconds
tVals = (-5:time_interval:1);  % -5 to 1 in steps of 0.04
% Equation
y = @(t) t.^2+3.*t+4;
yVals = y(tVals);   % t will take on the values of tVals
% Plot the result
plot(tVals, yVals, '-r'); % Plots t-values vs y-values; in default color (blue)
% Label the Graph
xlabel('Time (seconds)'); % Labels x-axis
ylabel('Distance (meters)'); % Labels y-axis
title('Time vs. Distance'); % Titles the graph
% Find min/max value of y and time when it occurs
[ymax, t1] = max(yVals);
[ymin, t2] = min(yVals);
% Print Part a
fprintf('The max value of y is %.2f meters and occurs at t=%.1f seconds \n', ymax, tVals(t1));
fprintf('The min value of y is %.2f meters and occurs at t=%.1f seconds \n', ymin, tVals(t2));
The max value of y is 14.00 meters and occurs at t=-5.0 seconds 
The min value of y is 1.75 meters and occurs at t=-1.5 seconds

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Mark Dillon 2015-7-22

Thank you! That helps a lot.

Is it possible to turn that into a loop?

Star Strider 2015-7-22

My pleasure!

You could turn it into a loop, but that would produce slower and less efficient code. One of MATLAB’s strengths is the vectorisation ability I used here, specifically to avoid a loop.

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