Catching a warning to avoid matrix singularity

My program calls a nested function. That nested fanction gets the 'number of iterations' as the input. Sometimes, the number of iterations is high and leads to singular matrix. I want to reduce the number of iterations if and only if the Matlab shows a singularity warning otherwise I want to leave it as high as possible. The reason is singluarity warning reduce the running time signifincatly (I prefer iteration as high as possible to increase the accuracy of my program).

Here is an example code

function some_out_put = main_function(x)
    global iteration 
    some_out_put = my_nested_function(x, iteration) % the nested fuction that gets singular sometimes
end

%%%%%%%%% my main implementation %%%%%%%
global iteration
iteration = 100;
for i=1:1:1000
    x = X(i)                  % X is a array of numbers
    y(i) = main_function(x) 
    % I want to reduce iteration if warning occurs (iteration = iteration - 1) but I need a block to catch it.
end

Answer 1

[Robert U]

Hi Mostafa Nakhaei,

quite similar to what you describe is shown in the documentation: https://de.mathworks.com/help/matlab/ref/lastwarn.html?s_tid=srchtitle

In order to clear the lastwarn before checking your particular warning case, use

lastwarn('');

https://de.mathworks.com/matlabcentral/answers/39993-how-to-clear-last-warning

More important for further work: Do not use global variables if not absolutely necessary. There are hundreds of threads arguing global variable troubles that are easily avoided by not using global variables.

Kind regards,

Robert

[Mostafa Nakhaei]

Thank you Robert