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dbdown

Reverse dbup workspace shift

Description

example

dbdown changes the current workspace and function context to the workspace and function context of the called MATLAB® function or script in debug mode. You must issue the dbup command at least once before you issue this command. dbdown is the opposite of dbup.

Multiple dbdown commands change the workspace and function context to each successively executed MATLAB function or script on the stack until the current workspace and function context is the line at which MATLAB is paused. You do not have to move back to the paused line to continue execution or to step to the next line.

example

dbdown n changes the current workspace and function context to the workspace and function context of the called function or script that is n levels lower on the stack. Running dbdown n is equivalent to running the dbdown command n times.

Examples

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Use the dbup and dbdown commands to view the current and calling function workspace of a function.

Create a file myfile.m that contains these statements.

function n = myfile(x)
n = myfunc(x-1);

function z = myfunc(y)
z = 2/y;

Set a breakpoint at myfunc and run myfile with an input of 1. MATLAB pauses in the function myfunc, at the line z = 2/y.

dbstop in myfile>myfunc
myfile(1);
5   z = 2/y;

Call whos to view the variables in the current workspace.

whos
  Name      Size            Bytes  Class     Attributes

  y         1x1                 8  double 

The workspace contains the variable y, which is in the workspace context for myfunc.

Run the dbup command to switch to the workspace of the calling function, myfile. Call whos to view the variables in the new workspace.

dbup
whos
In workspace belonging to myfile (line 2)
  Name      Size            Bytes  Class     Attributes

  x         1x1                 8  double 

The workspace contains the variable x, which is in the workspace context for myfile.

Run the dbdown command, and then call whos.

dbdown
whos
In workspace belonging to myfile>myfunc (line 5)
  Name      Size            Bytes  Class     Attributes

  y         1x1                 8  double              

The workspace once again contains the variable y, which is in the workspace context for myfunc.

Use the dbup and dbdown commands to change the current workspace and function context to any workspace and function context on the stack with one step.

Create a file myfile.m that contains these statements.

function n = myfile(x)
n = myfunc1(x-1);

function m = myfunc1(y)
m = myfunc2(2/y);

function p = myfunc2(z)
p = (z-1)/3;

Set a breakpoint at myfunc2 and run myfile with an input of 1. MATLAB pauses in the function myfunc2, at the line p = (z-1)/3.

dbstop in myfile>myfunc2
myfile(1);
8   p = (z-1)/3;

Call whos to view the variables in the current workspace.

whos
  Name      Size            Bytes  Class     Attributes

  z         1x1                 8  double    

The workspace contains the variable z, which is in the workspace context for myfunc2.

Run the dbup command to switch to the base workspace. Call whos to view the variables in the new workspace.

dbup 2
whos
In workspace belonging to myfile (line 2)
  Name      Size            Bytes  Class     Attributes

  x         1x1                 8  double      

The workspace contains the variable x, which is in the workspace context for myfile.

Run the dbdown command to switch to the workspace of myfunc2 with one step and then call whos.

dbdown 2
whos
In workspace belonging to myfile>myfunc2 (line 8)
  Name      Size            Bytes  Class     Attributes

  z         1x1                 8  double  

The workspace once again contains the variable z, which is in the workspace context for myfunc2.

Input Arguments

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Number of levels to move on the call stack, specified as a positive integer scalar.

Introduced before R2006a