Undefined function 'min' for input arguments of type 'sym'.

I'm attempting to run this code:

syms x1 x2 n;
assume(n>=0);
f = 2*x1^2 + 2*x2^2 - 2*x1*x2 + 2*x2^4 - 8*x1 + 5;
x = [200;-200];
m = solve (subs(f,[x1,x2],x + gam^n * d) <= subs(f,[x1,x2],x) + c*gam^n * gradx.'*d,n,'Real',true);

This returns the output

m =

Dom::Interval([0], [log(((184569509574205728450482700682269373180522852473434683651^(1/2)*486498208513403250724216051735683681829508695373292628743349050048000000000000000000000000^(1/2))/486498208513403250724216051735683681829508695373292628743349050048000000000000000000000000 - 174085952029516886891/9060546018411093202398740995200000000)^(1/3) - 5120384012576201153/(2359472952176702208291600000000*((184569509574205728450482700682269373180522852473434683651^(1/2)*486498208513403250724216051735683681829508695373292628743349050048000000000000000000000000^(1/2))/486498208513403250724216051735683681829508695373292628743349050048000000000000000000000000 - 174085952029516886891/9060546018411093202398740995200000000)^(1/3)) + 2/480009)/log(7/10)])

So far, so good. But then I try and take the minimum of the interval:

min(m)

And I get:

Undefined function 'min' for input arguments of type 'sym'.

What's going on, and how do I fix it?

Answer 1

[Walter Roberson]

Try double(m) and see what that returns. If that fails, vpa(m) should at least convert the log etc. into decimal.

As it is a non-empty interval, the min() of it will be the first operand of Interval(), namely the 0.