I'm working with the m-file editor of MATLAB and I need to jump from one line to another.
If I need to jump from inside a For...end, I can't use the usual "while"
technique.
Is there anyway to jump from a line to another, like goto in C?
There is no goto statement in MATLAB, but there are a few other commands for use with loops that may help you:
continue: This statement will skip the remaining commands in a for or while loop and move on to the next iteration.
break: This statement will terminate execution of a for or while loop.
There is no goto in matlab. However, this does not say you cannot structure your code to use an {if, else, elseif, end} structural form for your code. Or use a {switch, case, end} form. Or call a function (or subfunction or nested function) to solve your problem. Or use a continue/break to structure your code. One can always solve these problems using one of the existing forms of flow control available.
The use of functions can improve your code in other ways, often by making it more modular, and therefore easier to debug and write.
that solves the problem easily:
caseno = input('input your case no');
switch (caseno)
case 1
disp('this first section will run');
case 2
disp('this second section will run');
otherwise
disp('wrong case no');
end
for j = 1: 1: 24
% LABEL start
a = a + j;
if a > 10
goto('start') % If condition satisfied goto label start
return
else
a = a + 1;
end
end
Related
I use worksheet (not document mode).
I know one can do Edit>Remove Output>From Worksheet to "Removes Maple output from all execution groups in a worksheet."
But I could not find a command to do this. I need to do this, since when I run a loop as in
for i from 1 to n do
some_function();
od
And the function above say prints to the screen (i.e. worksheet currently open) lots of information, then the worksheet slows down and I really also do not want to see the logging from all the calls accumulated any way. I just need to see prints from one iteration only at a time.
(Maple has other problems with having large output accumulate in worksheet also, but this is for another topic).
I'd like to do something like this
for i from 1 to n do
some_function();
delete_all_output_in_current_worksheet();
od;
So only one call's output shows up as the some_function is running.
In Matlab, this is easily done using clc which clears the command windows in Matlab.
Is there something like the above in Maple?
Maple 2018.1 on windows.
There is no programmatic way to clear all the output of the current worksheet.
But you can push the running result from some_function() (each time through the loop) to Embedded Components, eg. TextBox, MathContainer, etc.
You don't even have to manually insert such Components from the palettes. Instead you can use the DocumentTools:-Tabulate command to programmatically insert a tabulated collection of components right after the current Execution Group.
For example, as 1D code in a Worksheet, you could have these blocks of code in three separate Execution Groups.
restart;
and,
some_function:=proc(i)
int( sin(x)^i, x);
end proc:
Leafcutoff := 150:
and,
# Put all this in the same Execution Group
for i from 1 to 111 by 10 do
res[i] := some_function(i);
K := MmaTranslator:-Mma:-LeafCount(res[i]);
if K <= Leafcutoff then
L := res[i];
else
L := sprintf("LeafCount > %a",Leafcutoff);
end if;
DocumentTools:-Tabulate(
[["i","LeafCount","result"],
[sprintf("%a",i), K, L]],
':-weights'=[10,10,40],
':-fillcolor'=((T,i,jj)->`if`(i=1,"grey",
"white")),
':-widthmode'=':-pixels',
':-width'=600);
Threads:-Sleep(1.5); # delay at least 1.5 sec
end do:
DocumentTools:-Tabulate([[]]):
I put in a time-delay of 1.5 seconds just to illustrate it working. You can adjust that, or remove it.
The last call to Tabulate is only there to blank it out, when the loop is finished.
The GUI Table inserted by Tabulate actually appears in a region right after the Execution Group. Only one such region appears, per Execution Group. Basically, each call to Tabulate overwrites that region.
If you changed the end do: to end do; then all the regular output would also be shown, as usual for a loop.
I use dbstop error a lot when working in Matlab. A good portion of the time, a mistake causes errors to be thrown inside of built-in [m-file] functions, which then causes Matlab to stop execution and open the file. However, it's almost never helpful to debug inside of the built-in file, so this ends up disrupting my workflow. Might there be a way to set things up so that Matlab backs out of the built-in file in the debugger (never opening it), leaving me at the function call?
Although I've never found a way to tackle this problem properly, it's fairly easy to hack together a workaround:
Create a script containing something along these lines:
S = dbstack();
file_paths = cellfun(#which, {S.file}, 'UniformOutput', false);
builtins = ~cellfun('isempty', strfind(file_paths, matlabroot()));
stack_depth = find(~builtins, 1, 'first');
for ii = 1:stack_depth-1
dbup(); end
Save it somewhere that makes sense to you, and place a shortcut to it in the MATLAB toolbar.
Then, whenever this problem occurs, you just click on your little shortcut, which will automatically take you to the first non-builtin function in the debug stack.
Based on Rody's answer and feedback from Mathworks, this is the closest you can get at this point (R2016b):
S = dbstack('-completenames');
builtins = ~cellfun('isempty', strfind({S(:).file}, matlabroot()));
stack_depth = find(~builtins, 1, 'first');
hDocument = matlab.desktop.editor.findOpenDocument(S(1).file);
matlab.desktop.editor.openAndGoToLine(S(stack_depth).file,S(stack_depth).line);
hDocument.close();
if stack_depth == 2
dbup();
end
This shortcut will:
Open up the closest user function to the correct line.
Close the builtin function that opened when the error was thrown.
If the error happened only one level away from a user function, switch to that workspace.
The problem is that dbup() only works once - after the call, execution in the script stops. There's no function to switch to an arbitrary place in the stack.
Is there any way to stop the execution of a matlab program from the debugger like ctrl+c does, but then being able to continue execution (like you can in say c#)?
If not, is there any better way to workaround this other than trying to pre-emptively set break points or dbstop statements in your matlab code?
I would like to be able to interrupt a long running simulation to look at the current state and then continue the simulation.
The two options I'm currently using/considering are
dbstop commands (or (conditional) breakpoints) in the code.
Drawback is that sometimes I don't want to stop the simulation for a few hours, sometimes want to stop after only a few seconds (and I don't necessarily know that in advance) and this doesn't work well with this approach: If I set the break condition to break every 5 minutes, I can't leave matlab running for hours without interaction. If I set the condition to higher, I have to wait too long for the condition to hit.
include code to save the workspace every few seconds/minutes and import the workspace into a second matlab instance. Drawback is that this is a huge hassle and also doesn't necessarily allows me to resume the simulation with the state of the saved workspace then step through the code for a few iterations.
I'm hoping there is a better solution than either of the 2. Thanks for any advice!
Edit: I think what I'm going to do is write simple matlab function that checks an environment variable or a file on disk every iteration and calls dbstop if I set a flag in this file or env. This way I can control when (and if needed which of several) the breakpoint hits from outside matlab by editing the file. Messy, but should work.
This is not necessarily the best way, but you could simulate a file-based signal/interrupt framework. It could be done by checking every once in a while inside the long simulation loop for the existence of a specific file. If it does, you enter interactive mode using the keyboard command.
Something along the lines:
CHECK_EVERY = 10; %# like a polling rate
tic
i = 1; %# loop counter
while true %# long running loop
if rem(i,CHECK_EVERY) == 0 && exist('debug.txt','file')
fprintf('%f seconds since last time.\n', toc)
keyboard
tic
end
%# ... long calculations ...
i = i + 1;
end
You would run your simulation as usual. When you would like to step in the code, simply create a file debug.txt (manually that is), and the execution will halt and you get the prompt:
2.803095 seconds since last time.
K>>
You could then inspect your variables as usual... To continue, simply run return (dont forget to temporarily rename or remove the file). In order to exit, use dbquit
EDIT: Just occurred to me, instead of checking for files, an easier solution would be to use a dummy figure as the flag (as long as the figure is open, keep running).
hFig = figure; drawnow
while true
if ~ishandle(hFig)
keyboard
hFig = figure; drawnow
end
%# ...
pause(0.5)
end
With the release of R2016a, you can just hit the Pause button in the code editor and it will halt right away. The keyboard shortcut is Ctrl+F5.
To pause the execution of a program while it is running, in the Editor tab, click the Pause button. MATLAB pauses execution at the next executable line*.
When your code is running, the Start button will turn into a pause:
Another change with this release is the ability to add/remove breakpoints while running. Previously you couldn't do this, apparently.
You can set a conditional breakpoint in the MATLAB Editor. You can also use DBSTOP to do this. For example, this will set a conditional breakpoint in the file myFcn at line 20 which will stop execution when a loop variable i is a multiple of 500:
dbstop in myFcn.m at 20 if rem(i,500) == 0
Then you can continue execution after you inspect some of your variables.
If saving the workspace to a file is a good proxy for what you want, how about making a simple GUI with a toggle button. In your code, check the state of the button. If the button is depressed, save the state, update a static text to reflect time stamp of last save, unpress the button. Optionally, have a conditional breakpoint based on the state of that toggle button.
Here is an alternate solution using the waitinput File Exchange submission.
The advantage is that you can use it from whithin the current session or in cases where it is troublesome to set up a file. Also it won't leave a file behind on the computer.
The downside is there as well unfortunately, you need to wait for the checking moment before you can terminate and it costs a little bit of time.
for t = 1:10
pause(3) %Doing some calculations
str = waitinput('Enter 1 if you want to stop ',5);
if ~isnan(str)
keyboard; % Enter dbcont if you want to continue from here
end
['moving on, it is now: ' datestr(now)]
pause(3) %Doing some more calculations
end
If you want, you can prevent lines being printed to the screen. In this case you need to enter the input at the time the figure window is open (Look in your start bar on windows).
To summarize, the short code that you can put somewhere like a conditional breakpoint would be:
if ~isnan(waitinput('',5))
keyboard;
end
After certain version (I don't know which one exactly):
Windows: Ctrl + F5
Mac: Command + F5 (I guess)
Unix: I am looking for answer too
After 2016a, there is a button for that on the interface too.
I have a script that is running a lot more time than I expected, it has been running for the last 3 days and only achieved 55% progress.
I would be perfectly happy to stop it at about 67% (I can live without the remaining 33%) But If I stop it now (ctrl+c or ctlr+break), I will lose all the data.
So is there a way to pause Matlab, perhaps into debug mode so I can check the variables without losing data?
The command (needs to be input manually before you start your function!)
dbstop if error
should catch a ctrl-c and leave you in debug mode.
I assume that you are doing something iteratively here and not relying on a built-in matlab function.
The way I usually solve the issue you have is to have an iteration counter and an if statement on that counter - when the condition is met, the statement has a breakpoint.
Something like this:
itCounter = 0;
itHalt = 100;
while (someCondition)
if (itCounter == itHalt)
itCounter = 0; %<= Put a breakpoint here
else
itCounter = itCounter+1;
end
% Here you calculate away whatever you need to calculate
end
This way, in every itHalt iterations you get a breakpoint. Also, since we're dealing with matlab, you can change the value of itHalt as you see fit as soon as the breakpoint is hit.
I'm thinking to an alternative solution:
Let's have a script which basically consists of a main loop.
The script periodically writes information about the execution status (e. g. the number of iteration done) into a log file.
Also, the script periodically reads a number from the input file
1 meaning "continue"
0 meaning "stop the script execution"
At the beginning of the simulation, 1 is written in the file.
The user can read the log and can decide, at a certain point, to stop the script.
To do it, he has just to change 1 to 0 in the file as save it.
An if section exemines the value read on it.
If 1, nothing appens and the script continues running.
If 0, a break statement terminates the main loop and the script stops.
Just before the break statement, in the if section, the script saves the whole workspace into a .mat file.
The user has now access to MatLab (he can evan close MatLab) and can look, for example, at the output files generated up to that moment by the script, process them, make somo plot and so on.
Then he might decide to continue the execution of the script from the point in which it has been stopped.
At the begining of the script, a variable controls the way the script has to be executed:
Mode 0: start from the beginning
Mode 1: resume the script
An if - else section maneges the user selection.
In particular, if Mode 1 is selected, the script loads the previously saved workspace (stored in a .mat file), then the value of some variables of the script are set to the old values.
As an example: the script was stopped when the index of the for loop was, say, 100.
if the for loop is defined as
for i=start_loop_1:100000
in the Mode 1 of the if, start_loop_1 is set to i+1 (the value of i was saved in the .mat file).
This allows the loop "continuing" the execution from the point in which it was stopped.
In order to effectively "resume" the running of the script, some other variables used in the script might require to be managed in the same way in the Mode 1 section.
In tha case of a "big", "complicated" script this might be difficult, but ... not impossible
This solution has been implemented in the following script.
I can see a potential criticality consisting in the unlucky case in which the user saves the file containing 1,0 at the same time the script reads it.
% Flag to select the running mode
% Mode 0: start from the beginning
% Mode 1: resume the running
continue_my_script=1;
% if "Mode 1" has been selected, the "old" workspace is loaded and some
% variables are properly set
if(continue_my_script == 1)
load my_script_data
start_loop_1=i+1;
start_loop_2=1;
% if Mode 0 has been selected some variables are set to their default value
else
start_loop_1=1;
start_loop_2=1;
% counter to enable writing of the log file
cnt_log=0;
% counter to enable reading the "go / no go" input file
cnt_go=0;
end
% Definition of the condition for writing the log file (in this case, a
% certain number of iterations")
log_iter=13;
% Definition of the condition for reading the "go / no go" input file (in
% this case, a certain number of iterations")
go_nogo_iter=20;
% Starting point of the "real script"
for i=start_loop_1:100000
% Increment the log counter
cnt_log=cnt_log+1;
% if "log_iter" have been done, update the log file
if(cnt_log == log_iter)
cnt_log=0;
t=clock;
fp=fopen('my_script_log.log','wt');
fprintf(fp,'i= %d at %d %d %f\n',i,floor(t(4)),floor(t(5)),t(6));
fclose(fp);
end
% Another loop of the script
for j=start_loop_2:100000
a(i,j)=sqrt(i);
end
% Increment the "read input file" counter
cnt_go=cnt_go+1;
% if "go_nogo_iter" have been done, read the go_nogo input file
if(cnt_go == go_nogo_iter)
cnt_go=0;
fp1=fopen('my_script_go.log','rt');
go_nogo=fscanf(fp1,'%d');
fclose(fp1);
% If the user made the decision to stop the execution, save the workspace
% and exit; otherwise ... do noting, just continue running
if(go_nogo == 0)
save my_script_data
break;
end
end
end
Hope this helps.
Okay, just to rephrase what I said in the comments with inputs from other users who commented. If your script is a MATLAB script, (Not a function), all the variables will be accessible from the workspace as long as you did not explicitly called 'clear' in the script if the script is stopped. In the usual case, ctrl+c will terminate the running script. The MATLAB variables used in the script will still be accessible from the MATLAB Workspace.
I don't think there is anything you can do while the code is already running, unless you put some hooks in place beforehand. Some of these other suggestions are good for that. Here is another one that I like: say you are leaving for the night, but coming back the next day, so you want your code to run for 14 hours and then stop and be waiting for you with however much data it got to in that time.
start_time = now;
final_time = start_time + 10/86400; % datenums are in days in Matlab, so +14/24 for 14 hours
% alternative: final_time = datenum('12-Aug-2015 09:00:00');
while now < final_time
% do work
disp('Working...')
pause(1)
end
% potential clean up code to save results
disp('Clean up code.')
I want to delete some variables that I have declared in command window in matlab, I tried clear all but it didn't work. I typed the following in the command window,
e.g.
a = 10;
str = 'a';
clear all
Matlab doesn't delete them, why?
Is there any function that can do this for me?
1)
If you have redefined function clear (e.g. by a variable or function), you can use the builtin function to execute built-in clear function.
I.e. you can use
builtin('clear','all')
to clear all variables,
respectively
builtin('clear','clear')
to redefine clear to the built-in clear function and then use it normally
clear all
2) If this was not the solution of your problem, could you show us the output of the following code?
a = 10;
str = 'a';
builtin('clear','all')
builtin('who')
To clear all of your variables in matlab you type:
clear
If you want to clear a specific variable, for instance "a" you tpye:
clear a
I suspect your problem is that you have named a variable "all" so when you use clear all you end up only clearing the variable all.
You should be careful about what names you are giving to your variables. You can useexist {variable} to check if the variable you want to assign is already used by a matlab function.
use "Clear" only it will work or u want to remove particular variable the put variable name in last of " Clear Var_name"