I cherry-picked that patch to MXE Octave here:
https://hg.octave.org/mxe-octave/rev/8df7db467c66

Should be in the next minor release of Octave (or the nightlies).

The problem described by the previous post should be fixed now, in 197b5a882a41 (but not in relases 1.6.2 made just now).

works for me now on 8.0.0 and current mercurial of struct (8fcb2a90702c) and optim (83eefe952baa) packages.

octave:1> pkg load optim
octave:2> test fmincon
PASSES 6 out of 6 tests
octave:3> test lsqnonlin
PASSES 2 out of 2 tests
octave:4> pkg list
Package Name  | Version | Installation directory
--------------+---------+-----------------------
          io *|   2.6.4 | /home/arburgers/octave_8/io-2.6.4
       optim *|   1.6.2 | /home/arburgers/octave_8/optim-1.6.2
  statistics *|   1.4.3 | /home/arburgers/octave_8/statistics-1.4.3
      struct *|  1.0.18 | /home/arburgers/octave_8/struct-1.0.18

I confirm that fmincon and lsqnonlin are broken on 7.1.0.

Yes, when I do "pkg load optim" it also loads io 2.6.4, optim 1.6.1, statistics 1.4.3 and struct 1.0.17.

The struct package does have a fields2cell.oct inside it but there is no fields2cell in the path. Something looks broken with the struct package for me. Reinstalling it with "pkg install -forge struct" gave a list of errors about "verror". I'll have to debug that separately.

Do "test lsqnonlin" and "test fmincon" work for you on Octave 7.1.0 or later?

Retitling this bug and setting it to 7.1.0.

Also, for Octave 8 and optim 1.6.1 the tests still fail but the error is different, referring to "fields2cell".

octave:2> test fmincon
***** test
 ## equality constraint
 objective_function = @ (p) p(1)^2 + p(2)^2;
 pin = [-2; 5];
 constraint_function = @ (p) - (p(1)^2 + 1 - p(2));
 [p, objf, cvg, outp] = fmincon (objective_function, pin, [], [], [], [], [], [], @ (p) {[], constraint_function(p)}{:}, optimset ("Algorithm", "lm_feasible"));
 assert (p, [0; 1], 1e-6)
!!!!! test failed
'fields2cell' undefined near line 75, column 14


octave:4> test lsqnonlin
***** test
 t = [0 .3 .8 1.1 1.6 2.3];
 y = [.82 .72 .63 .60 .55 .50];
 yhat = @(c,t) c(1) + c(2)*exp(-t);
 opt = optimset('TolFun',1e-10);
 [c,resnorm,residual] = lsqnonlin(@(c)yhat(c,t)-y,[1 1],[0 0],[],opt);
 assert (c, [ 0.47595; 0.34132], 1e-5)
 assert (resnorm, 3.2419e-004, 1e-8)
 assert(residual, [-2.7283e-003, 8.8079e-003, -6.8307e-004, -1.0432e-002, -5.1366e-003, 1.0172e-002], 1e-5)
!!!!! test failed
'fields2cell' undefined near line 75, column 14

This minimal example works under Octave 6.4.0 but throws an error in Octave 7.0.90 (plus, there are a couple of warnings when loading the optim package):

pkg load optim

x = (0:0.01:10).';
y = @(p) p(1) + p(2)*sin(2*pi*p(3)*x);

p0 = [0.3 0.5 0.2];
y0 = y([0.37 0.63 0.21]) + (rand(size(x))-0.5);

p_fit = lsqnonlin(@(p) y(p) - y0,p0);
plot(x,[y0,y(p_fit)])

I get this error:

error: : function called with too many inputs
error: called from
    @<anonymous>
    __dfdp__ at line 304 column 15
    __nonlin_residmin__>@<anonymous> at line 329 column 26
    __jacobian_constants__>@<anonymous> at line 121 column 11
    __lm_svd__ at line 196 column 9
    __nonlin_residmin__ at line 452 column 25
    nonlin_residmin at line 98 column 25
    lsqnonlin at line 264 column 21
    optim_bug at line 9 column 7

It seems to boil down to line 316 in \_\_nonlin_residmin\_\_

f.f = @ (varargin) f.f (varargin{:}) - obs;

which doesn’t seem to be allowed anymore.