This member function initializes the invoking function as a piecewise linear function whose segments are defined by the two argument arrays x and v. More precisely, the size n of array x must be equal to the size of array v, and if the created function is defined on the interval [xmin,xmax), its values will be:

• v[0] on interval [xmin, x[0]),
• v[i] + (t-x[i])v[i+1]-v[i])/(x[i+1]-x[i]) for t in [x[i], x[i+1]) for all i in [0, n-2] such that x[i-1] != x[i], and
• v[n-1] on interval [x[n-1],xmax).