You should first create the horizontal sine and then rotate it for pi/2 using rotation matrix to get the vertical sine. You can play with coefficients of Sine1 to get exactly what you wish.
x = linspace (-5,5, 51)';
Sine1(:,1) = x;
Sine1(:,2) = 0.3 * sin(x);
theta = pi/2;
RotationMatrix = [cos(theta) -sin(theta); sin(theta) cos(theta)];
Sine2 = [Sine1(:,1),Sine1(:,2)] * RotationMatrix;
hold ('on');
plot (Sine1(:,1),Sine1(:,2));
plot (Sine2(:,1),Sine2(:,2));
hold ('off');
box ('on');
