A command to create an ISpline from a list of coefficients.
Settings

Xmin and Xmax

define the domain of the polynomial spline.

Degree

defines the degree of the polynomial spline.

Coefficients

define the coefficients of the basis polynomials.

Interior knots

define the positions in the domain where continuity conditions are defined.
Behaviour
The number of coefficients and the number of interior knots must satisfy the following relation:
numberOfCoefficients = numberOfInteriorKnots + degree 
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