How can I resolve the "not enough input arguments" error message for the optimization solver?

Keagan Yates

2021 9 1

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Hello, I am a graduate student doing extra practice with optimizations outside of the classroom with the MATLAB R2018b version. The problem is a simple classic based around the optimization of a two bar truss system. I created the following objective function:

%x(1) represents height and x(2) represents diameter

function f = objectivefunc(x) 
    density = 0.3;
    thickness = 0.15;
    base = 60;
    force = 66;
    modulus = 3.00E4;
f = density*2*pi*x(2)*thickness*length; %Weight Equation 
end 

I then created the following constraint function:

function [c, ceg] = Constraintfunc(x) 
% nonlinear inequality constraints
density = 0.3;
thickness = 0.15;
base = 60;
force = 66;
length = sqrt((base/2)^2 + x(1).^2);
modulus = 3.00E4;
c = (force*length) / (2*thickness*pi*x(2)*x(1)) - 100;
    ((force*length) / (2*thickness*pi*x(2)*x(1))) - (pi^2*modulus*(x(2))^2+(thickness^2)) / (8*(length)^2);
    (force*length^3) / (2*thickness*pi*x(2)*(x(1))^2*modulus) - 0.25;
%nonlinear equality constraints   
ceq = [];
end

I define the starting "x" as [30,3] and specify test upper and lower bounds as [50,10] and [5,1] respectively. Upon trying to use the optimization solver I get the error message "Not enough input arguments." I fixed a previous error where I was trying to pass two variables into the solver and thought that would resolve it, but I am still unfortunately stuck. Any help or clarity would be greatly appreciated.