how to use dbstop if naninf

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Habib
Habib on 10 May 2013
Commented: John Hatrick on 16 Mar 2018
I want to ask matlab to stop anywhere in my functions, a variable becomes nan or inf. I defined a function buggy(x) (which is a matlab example in help page of dbstop).
function z = buggy(x)
n = length(x);
u=8/0
z = (1:n)./x;
I just added one line ( u=8/0) to see how dbstop if naninf works. when I ran, matlab started violating. The response is in the following code:
>> dbstop if naninf
>> buggy(3)
u =
Inf
NaN/Inf breakpoint hit for buggy on line 3.
Stopping at next line.
3 u=8/0
4 z = (1:n)./x;
20 if ~isfloat(value)
20 if ~isfloat(value)
399 if numel(var) > numelLimit
20 if ~isfloat(value)
20 if ~isfloat(value)
399 if numel(var) > numelLimit
20 if ~isfloat(value)
20 if ~isfloat(value)
399 if numel(var) > numelLimit
20 if ~isfloat(value)
20 if ~isfloat(value)
399 if numel(var) > numelLimit
20 if ~isfloat(value)
20 if ~isfloat(value)
399 if numel(var) > numelLimit
20 if ~isfloat(value)
20 if ~isfloat(value)
399 if numel(var) > numelLimit
20 if ~isfloat(value)
20 if ~isfloat(value)
399 if numel(var) > numelLimit
20 if ~isfloat(value)
...and continuing...
and matlab stays in debugging mode and if I try doing something in matlab, it freezez.
Am I using dbstop in a wrong syntax or a wrong place?
I want matlab to stop and any inf/nan that that I have produced in my own codes. apparently it stops in its own built-in matlab files as well.
  1 Comment
John Hatrick
John Hatrick on 16 Mar 2018
I have this problem too!
setting 'dbstop if naninf' finds tons of inf statements in MATLAB scripts I'm not using such as 'fsolve.m' and 'trustnleq.m.'
I want to find if a variable goes NaN; I don't care if the phrase 'inf' shows up in a script...
Respectfully, John

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Accepted Answer

Matt J
Matt J on 10 May 2013
You're definitely not doing anything wrong. It works fine for me. What version of MATLAB is this? Maybe try again after restarting MATLAB? Or maybe try reinstalling.
  1 Comment
Habib
Habib on 11 May 2013
Matlab 2009a. I have to upgrade to the 2012b in a few days. Thanks buddy for trying the code.

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