for the given data
x=1,2,3,4
f(x)=1.5,2,3,3.5
estimate of at x=2.5 and x=3.25 using cubic splines interpolation method
hints :
there will be three cubic cubic splines of the form
s0(x) = a 0 + b0(x-x0) + c0(x-x0)^2 + d0(x-x0)^3
s0(x) = a1 + b1(x-x1) + c1(x-x1)^2 + d1(x-x1)^3
s0(x) = a2 + b2(x-x2) + c2(x-x2)^2 + d2(x-x2)^3
to find 12 constants (unknowns) above we need at least 12 conditions
INTERPOLATING CONDITIONS:
1) s0(x0) = f(x0)
2) s1(x1) = f(x1)
3) s2(x2) = f(x2)
CONTINUITY CONDITIONS:
1) s0(x1) = s1(x1)
2) s1(x2) = s2(x2)
3) s2(x3) = s3(x3)
FIRST DERIVATIVE CONDITIONS:
1) s0'(x1) = s1'(x1)
2) s1'(x2) = s2'(x2)
FIRST DERIVATIVE CONDITIONS:
1) s0''(x1) = s1''(x1)
2) s1''(x2) = s2''(x2)
TWO EXTRA CONDITIONS (BOUNDARY CONDITIONS)
1) s0''(x0) = 0
2) s2''(x2) = 0
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