Should it just return at the first FALSE?

Dmitri.
--

Octave's assert function was originally designed to be used in the Octave test suite where most test expressions have reasonable sizes.

But yes, it could be useful to limit the output that is displayed for this calling form.

You might try something like

assert (max (abs (a - b)(:)) < tol)

Dear GNU-Octave developers,

If you execute the following code in Octave, it will take forever.

tol = eps;
N = 1000;
a = rand(N, N);
b = rand(N, N);
assert(a, b, tol);

Obviously, one could rewrite the above code as follows:

tol = eps;
N = 1000;
a = rand(N, N);
b = rand(N, N);
assert(max(max(abs(a-b)))<=tol);

However, if you have a large testsuite with many calls to assert, your whole testsuite might be broken, just because a single assert fails. Rewriting the whole testsuite might be tedious. Now I'm considering the option to replace all my calls to assert by a custom version of assert which does not have such a performance issue.

Nevertheless, I think that it would be a good idea to limit somehow the length of the error message generated by assert, because nobody would read an error message with one million lines. For example, maximum 1000 differences larger than the tolerance could be reported. As an alternative, assert could just report the maximum error or the total number of values with a difference above the tolerance. A remark could be added, that the complete error message would be too long to display it.

Please let me know if such an option would be acceptable for you!
In that case I could create and submit a patch for assert.