Ode45 handles function error

My function ug data is got from edittext of GUI

function ut = ug(handles, x, y)

ut = handles.edit11.String

evalc(ut)

vg is like that

Question: When i put the formula to the push button of gui below to get the dy/dx = ug/vg i got error

Formula: for a=-5:1:5;

tspan = [a 6];

y0 = [-5 5];

[xx,yy] = ode45(@(x,y) (vg(handles, x, y))./(ug(handles, x, y)), tspan, y0);

plot(xx,yy,'-k','linewidth',2);

hold on

end

My code works if i create a function like ut=ug(x,y) .... but if i do like that i cant get datas from edittext. How can i activate the code in ode 45 with datas in edit text??

[Walter Roberson]

You should be using str2func instead of evalc()

But you have a problem that you have a division by 0. Your first formula crosses 0 slightly above x =-1 and the time is included in all of your timespan for a = -5:-1. This is a problem because you are dividing by that.

[esat gulhan]

Well

I change the formula and limits like that.So div/0 is not problem, i erased evalc(ut) in the function and write

function ut = ugs(handles, x, y)

ut = handles.edit11.String

str2func(ut)

end, and rewrite vg too

Formula: for a=1:1:5; (limits changed)

tspan = [a 6];

y0 = [-5 5];

[xx,yy] = ode45(@(x,y) (vg(handles, x, y))./(ug(handles, x, y)), tspan, y0);

plot(xx,yy,'-k','linewidth',2);

hold on

Now it gives new error,

Error using odearguments (line 90)

@(X,Y)UG(HANDLES,X,Y) must return a column vector.

[esat gulhan]

But if i change code like that

[xx,yy] =ode45(@(x,y) (1.5-0.8*y)./(0.8*x+0.5) , tspan, y0)

it works, but my wish to take formulas from the edit text of gui. I dont want to write all time manuel to the formula.