Input Help

Hello, this is my Eulers methods program. I am trying to make the user input an equation. For example, I want the user to input something like (x+y). However, I have the user to also input starting values of and x and y. When the user inputs these x and y values, it makes the (x+y) a constant. However, the values of x and y change which in turn should change the value of (x+y). But because it changed dydx to a constant originally, the value of (x+y) doesn't change even though it should. Here is my program so far. I've gotten advice to change the input to input s but I don't really know how that works. Could someone possibly edit my code so that it will do what it is supposed to? I'm hoping that if someone edits it correctly, i can understand what is going on. Thank you.

x=input('Input the initial value of "x":  ');
y=input('Input the initial value of "y":  ');
dydx=input('The change in y in terms of x is equal to: ','s');
value=input('Input the value of the unknown function in which you want to evaluate to. (i.e if you want y(3), type in 3) \n');
step=input('Input the step size you would like:  ');

for i=0:100

      dy=dydx*step;
      x=x+step;
      y=y+dy;
      if x==value
          fprintf('The estimated value of the function is %3.2f \n',y)
      end

end

Answer 1

[Walter Roberson]

I already gave you a specific reference to the code change you need in your existing thread on this topic, http://www.mathworks.com/matlabcentral/answers/21656-eulers-formula-program-help

[Teague]

Yes you did. I'm still having a difficult time after reading through the link you sent me. I'm sorry,