MATLAB Programming

8 Error Handling
end
function f2(x)
f3(x-1)
function f3(y)
x = log(y);
end
end
end
After enabling all warnings, run the M-file. The code generates a “Log of zero”
warning. In an M-file of this size, it is not difficult to find the cause of the
warning, but in an M-file of several hundred lines, this could take some time:
warning on all
f1(50,1)
Warning: Log of zero.
To simplify the debug process, enable backtrace mode. In this mode, MATLAB
reports which function generated the warning (f3), the line number of the
attempted operation (line 8),thesequenceoffunctioncallsthatleduptothe
execution of the function (f1>f2/f3), and the line at which each of these
function call was made (3 and 6):
warning on backtrace
f1(50,1)
Warning: Log of zero.
> In f1>f2/f3 at 8
In f1>f2 at 6
In f1 at 3
Example 2 — Enabling Verbose Warnings
When you enable verbose warnings, MATLAB displays an extra line of
information with each warning that tells you how to suppress it:
Turn on all warnings, disable backtrace (if you have just run the previous
example), and then enable verbose warnings:
warning on all
warning off backtrace
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