how to substitute an syms variable into known value and evaluate the result of the same equation that contain it?

i'm tying to generate a general equation for Bezier curve in polynomial form , differentiate it, then substitute the value of u by 0 or 1 in the general equation but i don't know how

% u incremental value
n=input('input the number of control points = ');
k= n-1
m=1;
   for  i=0:1:k;
       w=1;
       syms u 
        r(w,m)=factorial (k)/(factorial(i)*factorial(k-i))*u.^i*(1-u).^(k-i)
      w=w+1
      m=m+1
   end;
   syms u
   d=diff (r)
   syms u
   f= diff(r,2)
for u=1
    g1=(r)
end

Answer 1

[Walter Roberson]

g1 = subs(r, u, 1);
g0 = subs(r, u, 0);

[fatima saad]

sorry nothing happened its stop at f and Neglected g

[Walter Roberson]

n = input('input the number of control points = ');
k = n-1;
m = 1;

syms u 

for  i = 0 : k
  w=1;
  r(w, m) = factorial(k)/(factorial(i)*factorial(k-i))*u.^i*(1-u).^(k-i);
  w = w + 1;
  m = m + 1;
end;

d = diff(r,u)
f = diff(r,u,2)
g1 = subs(d, u, 1);
g0 = subs(d, u, 0);

[fatima saad]

also nothing ..thanks for help

[Walter Roberson]

I see no evidence that it did not calculate g1 or g0. It did not output them, but that does not mean it did not calculate them. Did you try displaying them?

Note: in MATLAB, if you have a semi-colon at the end of a statement, it means that the result of the statement is not to be displayed by default. The semi-colon in

g1 = subs(d, u, 1);

allows g1 to be calculated without displaying it. You can remove the semi-colon if you want it to be displayed

   g1 = subs(d, u, 1)

[fatima saad]

thank you so much ,that's where my fault i removed it and its worked thanks