How can I make my MATLAB simulation code run more efficiently? - performance

Question

I am creating a simulation to model a robot moving through river currents. The more code I add, the slower the simulation gets. Sometimes, it runs so slow that the buttons don't work. Does anyone know how I might speed it up?
It is possible that it might be my computer. A few times, the simulation ran flawlessly.
Code:
function CleanRiverSolutionsSimulation
%Initialize Figure
f = figure('Visible','off','Position',[250,250,1000,500],'Name','Clean River Solutions Simulation');
%Initialize variables (when changing these, don't forget to change them in
%the stop button function)
robot_position = [0 0 0];
last_robot_position = [-1 0 0];
time_data = [0];
depth_data = robot_position(3);
simulation_mode = 'paused'; %options: 'paused' 'running' 'stopped'
river_depth = 10;
water_flow_rate = 1;
%Initializes Plots
main_plot = axes('Units','pixels','Position',[50,225,500,250]);
data_plot1 = axes('Units','pixels','Position',[625,350,200,100]);
%Initializes Sliders
water_flow_slider = uicontrol('style','slider','position',[50 175 200 20],'min',0,'max',2.5,'callback',#callback_waterflow,'value',water_flow_rate);
water_flow_text = uicontrol('Style','text','String','River Water Flow','Position',[30 140 200 30]);
water_flow_text.String = sprintf('River Water Flow: %f m/s',get(water_flow_slider,'value'));
river_depth_slider = uicontrol('style','slider','position',[50 125 200 20],'min',0,'max',10,'callback',#callback_riverdepth,'value',river_depth);
river_depth_text = uicontrol('Style','text','String','River Depth','Position',[30 90 200 30]);
river_depth_text.String = sprintf('River Depth: %f m',get(river_depth_slider,'value'));
%Initializes Push Buttons
run_button = uicontrol('Style','pushbutton','String','Run','Position',[300 175 50 20],'callback',#callback_runbutton);
pause_button = uicontrol('Style','pushbutton','String','Pause','Position',[360 175 50 20],'callback',#callback_pausebutton);
stop_button = uicontrol('Style','pushbutton','String','Stop','Position',[420 175 50 20],'callback',#callback_stopbutton);
status_text = uicontrol('Style','text','String','Status','Position',[300 140 150 30]);
status_text.String = sprintf('Status: %s','Paused');
%After setup, makes figure visible
f.Visible = 'on';
%Environment Settings
riv_length = 20;
riv_width = 20;
%River flow settings
flow_dots = 4;
%Initialize Main Plot (when changing these, don't forget to change them in
%the stop button function)
plot3(main_plot,robot_position(1),robot_position(2),robot_position(3),'Marker', 'o','Color','r')
main_plot.XLim = [-riv_length/2 riv_length/2];
main_plot.YLim = [-riv_width/2 riv_width/2];
main_plot.ZLim = [-1*river_depth 1];
main_plot.XGrid = 'on';
main_plot.YGrid = 'on';
main_plot.ZGrid = 'on';
%Initialize time sequence (when changing these, don't forget to change them in
%the stop button function)
time = clock;
pausedStartTime = time(6)+60*time(5)+3600*time(4);
startTime = pausedStartTime;
pausedTime = 0;
totalPausedTime = 0;
%MAIN SIMULATION LOOP
while ishandle(f)
switch simulation_mode
case 'running'
%TODO-add forces and have the positions depend on the forces
%creates a time t to use in simulated equations
time = clock;
t = ((time(6)+60*time(5)+3600*time(4))-startTime-totalPausedTime);
%X
last_robot_position(1) = robot_position(1);
robot_position(1) = 0;
%Y
last_robot_position(2) = robot_position(2);
robot_position(2) = 0;
%Z
last_robot_position(3) = robot_position(3);
robot_position(3) = -4+2*sin(2*t); %just did a sin wave to show movement
%UPDATE MAIN PLOT
%update robot position
plot3(main_plot,robot_position(1),robot_position(2),robot_position(3),'Marker','o','Color','r')
%update robot velocity vector?
forward_vector = [robot_position(1)-last_robot_position(1),...
robot_position(2)-last_robot_position(2),...
robot_position(3)-last_robot_position(3)];
forward_unit_vector = forward_vector./norm(forward_vector);
hold(main_plot,'on')
plot3(main_plot,[robot_position(1) (robot_position(1)+forward_unit_vector(1))],...
[robot_position(2) (robot_position(2)+forward_unit_vector(2))],...
[robot_position(3) (robot_position(3)+forward_unit_vector(3))]);
%update river flow dots
for dot = 1:flow_dots
plot3(main_plot,-riv_length/2+(dot-1)*(riv_length/flow_dots)+mod((t/water_flow_rate),(riv_length/flow_dots)),10,0,'Marker','o','Color','b')
end
%update plot settings
main_plot.XLim = [-riv_length/2 riv_length/2];
main_plot.YLim = [-riv_width/2 riv_width/2];
main_plot.ZLim = [-1*river_depth 1];
main_plot.XGrid = 'on';
main_plot.YGrid = 'on';
main_plot.ZGrid = 'on';
hold(main_plot,'off')
%Update Data Plot 1 (depth)
time = clock;
time_data = [time_data ((time(6)+60*time(5)+3600*time(4))-startTime-totalPausedTime)];
depth_data = [depth_data robot_position(3)];
plot(data_plot1,time_data,depth_data)
title('Robot Depth')
data_plot1.XLim = [max(0,(((time(6)+60*time(5)+3600*time(4))-startTime-totalPausedTime)-15)),...
max(0,(((time(6)+60*time(5)+3600*time(4))-startTime-totalPausedTime)-15)+20)];
data_plot1.YLim = [-1*river_depth 1];
pause(0.1); %anything lower and the simulation won't pause
case 'paused'
pause(0.01); %need this or the sim won't start
case 'stopped'
%so far, this line is never run
end
end
%executes callback for water flow slider
function callback_waterflow(source,eventdata)
water_flow_text.String = sprintf('River Water Flow: %f m/s',get(water_flow_slider,'value'));
water_flow_rate = get(water_flow_slider,'value');
end
%executes callback for river depth slider
function callback_riverdepth(source,eventdata)
river_depth_text.String = sprintf('River Depth: %f m',get(river_depth_slider,'value'));
river_depth = get(river_depth_slider,'value');
end
%executes callback for run button
function callback_runbutton(source,eventdata)
switch simulation_mode
case 'stopped'
%Reinitialize time sequence
time = clock;
startTime = time(6)+60*time(5)+3600*time(4);
pausedTime = 0;
totalpausedTime = 0;
case 'paused'
time = clock;
currentTime = time(6)+60*time(5)+3600*time(4);
pausedTime = currentTime-pausedStartTime;
totalPausedTime = totalPausedTime + pausedTime;
pausedTime = 0;
end
simulation_mode = 'running';
status_text.String = sprintf('Status: %s','Running');
end
%executes callback for run button
function callback_pausebutton(source,eventdata)
switch simulation_mode
case 'running'
status_text.String = sprintf('Status: %s','Paused');
time = clock;
pausedStartTime = time(6)+60*time(5)+3600*time(4);
end
simulation_mode = 'paused';
end
%executes callback for run button
function callback_stopbutton(source,eventdata)
simulation_mode = 'stopped';
status_text.String = sprintf('Status: %s','Stopping');
%Reset all simulation data
robot_position = [0 0 0];
time_data = [0];
depth_data = robot_position(3);
%Reinitialize time sequence
time = clock;
pausedStartTime = time(6)+60*time(5)+3600*time(4);
startTime = pausedStartTime;
pausedTime = 0;
totalPausedTime = 0;
%Reinitialize Plots
plot3(main_plot,robot_position(1),robot_position(2),robot_position(3),'Marker','o','Color','r')
main_plot.XLim = [-riv_length/2 riv_length/2];
main_plot.YLim = [-riv_width/2 riv_width/2];
main_plot.ZLim = [-river_depth 1];
plot(data_plot1,time_data,depth_data)
status_text.String = sprintf('Status: %s','Data is reset.');
simulation_mode = 'paused';
end
end

Answer 1

matlab provides you tools to do this - it is called a profiler. try this
profiler on;
your_script_name;
profiler viewer;
from the output, you can tell which lines or functions cost most of your run time. I use it every time I need to speed up my matlab code.