Error using fsolve, indices not compatible

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!

[madhan ravi]

Dude provide the full code or attach your relevent script files

[Abigale Mattingly]

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;

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);

[madhan ravi]

but before the error I get this

Equation solved. The sum of squared function values, r = 5.652814e-22, is less than
sqrt(options.FunctionTolerance) = 1.000000e-03. The relative norm of the gradient of r,
2.261198e-11, is less than options.OptimalityTolerance = 1.000000e-06.

Optimization Metric                                         Options
relative norm(grad r) =   2.26e-11              OptimalityTolerance =   1e-06 (default)
r =   5.65e-22                              sqrt(FunctionTolerance) =  1.0e-03 (default)

>> 

[Abigale Mattingly]

Madhan, I don't understand your comment. I think you are missing part of your response? Thanks for the help!

[Abigale Mattingly]

Do you know how I may correct the error or why I am getting it?

[Kevin Chng]

I dont have error. I'm bit confusing. You should save them in one 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;
end

Open another script and run it :

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);

[Abigale Mattingly]

What do you mean I should save them in one script? You later said you opened another script.

[Abigale Mattingly]

I'm still getting an error.

[Kevin Chng]

Save them in the same path, and then run Untitled2.m.

Answer 1

[madhan ravi]

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

[Abigale Mattingly]

This worked, thank you so much!

[madhan ravi]

Anytime :)