MATLAB Functions

Last error message

str = lasterr
lasterr('')

Description

str = lasterr

returns the last error message generated by MATLAB.

lasterr('')

resets lasterr so it returns an empty matrix until the next error occurs.

Examples

Here is a function that examines the lasterr string and displays its own message based on the error that last occurred. This example deals with two cases, each of which is an error that can result from a matrix multiply.

function catch
l = lasterr;
j = findstr(l,'Inner matrix dimensions');
if j~=[]
    disp('Wrong dimensions for matrix multiply')
else
    k = findstr(l,'Undefined function or variable')
    if (k~=[])
        disp('At least one operand does not exist')
    end
end

The lasterr function is useful in conjunction with the two-argument form of the eval function:

eval('str','catchstr')

where catchstr examines the lasterr string to determine the cause of the error and take appropriate action. The eval function evaluates the string str and returns if no error occurs. If an error occurs, eval executes catchstr. Using eval with the catch function above:

clear
A = [1  2  3; 6  7  2; 0  -1  5];
B = [9  5  6; 0  4  9];
eval('A*B','catch')

MATLAB responds with Wrong dimensions for matrix multiply.