The following snippet:

(let ((v1 #m(1d0 2d0 3d0))
       (v2 #m(3d0 2d0 1d0)))
       (let ((interpolation (make-interpolation +linear-interpolation+
                        v1 v2))
         (accel (make-acceleration)))
    (evaluate interpolation 2d0 :ya v2 :x1 v1 :acceleration accel)))

throws an error on SBCL (1.0.34):

There is no applicable method for the generic function
#<STANDARD-GENERIC-FUNCTION C-ARRAY:ORIGINAL-ARRAY (1)>
when called with arguments
(NIL).
   [Condition of type SIMPLE-ERROR]

spline interpolation works. So, what am I missing?

Mirko