How to interpolate in between known data points..?

I have data at starting and the ending and I want to interpolate the data in between. Can any one suggest me best method to do it. for example:

 Y = peaks(100);
y = Y(50,:);
y(40:50) = 0;
figure();subplot(1,2,1);plot(x,y,'b');title('available data');ylabel('y');
hold on; plot(x,Y(50,:),'b.');legend('available','expected');
subplot(1,2,2);plot(x,Y(50,:),'b');ylabel('Y');title('expected');

dots in first plot of the above (or second plot) is expected and thick line indicates the available data. I want to interpolate in between using the data x<40 and x>50.

Answer 1

[Stephen23]

% Data:
Y = peaks(100);
x = 1:size(Y,2);
y = Y(50,:);
y(40:50) = 0;
% Interpolate zeros:
idx = y~=0;
yn = interp1(x(idx),y(idx),x,'spline');
plot(x,y,x,yn)
legend('missing','interpolated')

Giving:

Answer 2

[KSSV]

Read about interp1