- 22

- 0

**interpolant**

f(-pi)=4 f(-pi/2)=5/4 f(0)=1 f(pi/2)=-3/4 f(pi)=0

the function is (1/pi2 ) (x-pi)2 - cos2 (x-pi/2)

Don't know how to do this. I tried lagrange basis functions f(x0)(x1-x)/(x1-x0)+f(x1)(x-x0)/(x1-x0)

But it doesn't turn out right.

The answer for the first interpolant (interval -pi to -pi/2) is: 4-11(x+pi)/(2pi)