12 SUBROUTINE r8spline (N, X, Y, B, C, D)
16 INTEGER,
PARAMETER :: R8=selected_real_kind(12,100)
23 real*8 x(n), y(n), b(n), c(n), d(n)
58 IF ( n .LT. 2 )
RETURN
64 IF(x(ip1).LE.x(i))
then
66 write(6,9001) (x(ii),ii=1,n)
67 zbomb=sqrt(-1.0_r8/(x(1)*x(1)))
69 write(6,*)
' spline.for: code will stop.'
72 >
' ? UNORDERED ORDINATE ARRAY PASSED TO SPLINE SUBROUTINE:')
73 9001
FORMAT(1x,5(1x,1pe12.5))
77 IF ( n .LT. 3 )
GO TO 50
84 c(2) = (y(2) - y(1))/d(1)
87 b(i) = 2._r8*(d(i-1) + d(i))
88 c(i+1) = (y(i+1) - y(i))/d(i)
99 IF ( n .EQ. 3 )
GO TO 15
100 c(1) = c(3)/(x(4)-x(2)) - c(2)/(x(3)-x(1))
101 c(n) = c(n-1)/(x(n)-x(n-2)) - c(n-2)/(x(n-1)-x(n-3))
102 c(1) = c(1)*d(1)**2/(x(4)-x(1))
103 c(n) = -c(n)*d(n-1)**2/(x(n)-x(n-3))
109 b(i) = b(i) - t*d(i-1)
110 c(i) = c(i) - t*c(i-1)
118 c(i) = (c(i) - d(i)*c(i+1))/b(i)
125 b(n) = (y(n) - y(nm1))/d(nm1) + d(nm1)*(c(nm1) + 2._r8*c(n))
127 b(i) = (y(i+1) - y(i))/d(i) - d(i)*(c(i+1) + 2._r8*c(i))
128 d(i) = (c(i+1) - c(i))/d(i)
135 50 b(1) = (y(2)-y(1))/(x(2)-x(1))