MATLAB: Error using fsolve, indices not compatible

fsolvematrix

I am trying to solve a system of equations using fsolve but I keep getting the following error: 
Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.
Error in root2d (line 4)
F(1)=(m*(x1-x3))-(y1-y3);
Below is a snippet of my code, with the function first followed by the main script.
function F = root2d(k,m,x1,y1)
x3 = k(1);
y3 = k(2);
F(1)=(m*(x1-x3))-(y1-y3);
F(2)=(sqrt(((y1-k(2))^2)+((x1-k(1))^2)))-1;
m = diff(y(xx1));
x0 = [0,0];
sol = fsolve(@(k)root2d(k,m,x1,y1),x0);
Note: x1 and x2 are scalars defined earlier in the code.
Can anyone help me fix this error? Thank you!

Best Answer

Alternatively a script can contain function at the end of your script in 2016b or later
r = 3;
f = 2;
x0 = 0;
x1 = -3;
x2 = 3;
y0 = 0;
y1 = x1^2;
y2 = x2^2;
rmag = sqrt(((x1-x0)^2)+((y1-y0)^2));
fi = asind(r/rmag);
thetas = 0.25;
x = x1:0.01:x2;
y = x.^2;
theta = randi([-90,90],1,1);
xx1 = (randi(length(x),1,1));
x1 = x(xx1);
y1 = y(xx1);
x2 = (sind(theta))+ x1;
f = @(y2) sqrt(((x1-x2)^2)+((y1-y2)^2))-1;
y2 = fsolve(f,1);
m = diff(y(xx1));
x0 = [0,0];
sol = fsolve(@(k)root2d(k,m,x1,y1),x0);     % function call
function F = root2d(k,m,x1,y1)       % function definition
x3 = k(1);
y3 = k(2);
F=[(m*(x1-x3))-(y1-y3);                   %changed this line and the error was avoided
(sqrt(((y1-k(2))^2)+((x1-k(1))^2)))-1];
end
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