Error showing "Undefined function 'vecline' for input arguments of type 'sym'."

Code:

function vectline(f,crdaxis,crdrange,step)
if max(size(crdaxis))==3
    if max(size(crdrange))==6

        xmin=crdrange(1);
        xmax=crdrange(2); 
        ymin=crdrange(3);
        ymax=crdrange(4);
        zmin=crdrange(5);
        zmax=crdrange(6);

        dx=(xmax-xmin)/step;
        dy=(ymax-ymin)/step;
        dz=(zmax-zmin)/step;

        [px,py,pz]=meshgrid(xmin:dx:xmax,ymin:dy:ymax,zmin:dz:zmax);
        junk=subs(f,{crdaxis(1),crdaxis(2),crdaxis(3)},{px,py,pz});

        junksize=size(junk);
        k=junksize(2);

        u=junk(:,1:k/3,:);
        v=junk(:,k/3+1:2*k/3,:);
        w=junk(:,2*k/3+1:k,:);

        quiver3(px,py,pz,u,v,w,0)
    else
        error('the size of the dimension does not match the range you specified')

    end

elseif max(size(crdaxis))==2
    if max(size(crdrange))==4

        xmin=crdrange(1);
        xmax=crdrange(2);
        ymin=crdrange(3);
        ymax=crdrange(4);

        dx=(xmax-xmin)/step;
        dy=(ymax-ymin)/step;

        [px,py]=meshgrid(xmin:dx:xmax,ymin:dy:ymax);
        junk=subs(f,{crdaxis(1),crdaxis(2)},{px,py});
        
        junksize=size(junk);
        k=junksize(2);

        u=junk(:,1:k/2);
        v=junk(:,k/2+1:k);

        quiver(px,py,u,v,0)

    else
        error('the size of the dimension does not match the range you specified')
    end

else
    error('vector field with more than 3 dimensions can not be plotted')
end 

In Command prompt I write the following:

>> syms x y
>> F=[-x,-y]
 
F =
 
[ -x, -y]
 
>> vecline(F,[x,y],[-2,2,-3,3],10)
Undefined function 'vecline' for input arguments of type 'sym'.

[Adam Danz]

I'm not aware of "vecline", perhaps it's a 3rd party function.

In either case, given the error message these are the possibilities

• you either don't have the function or...
• you have the function and it's not on the matlab path, or...
• you have the function and it's on the matlab path but does not receive inputs of type "sym".

You can start trouble shooting based on those possibilities. exist() and which() may be useful functions.

Answer 1

[Star Strider]

You misspelled it in your call to it.

You defined it as:

function vectline(f,crdaxis,crdrange,step)

however you called it as:

vecline(F,x,y,-2,2,-3,3,10)

Try this:

vectline(F,x,y,-2,2,-3,3,10)

[Adam Danz]

Good catch!

[Star Strider]

Thank you!