Lagrange

Purpose

Lagrange interpolation polynomials in interval -1<xi<1

Synopsis

lp = Lagrange (degree,deriv,xi)

Description

LAGRANGE Lagrange interpolation polynomials in interval -1<xi<1
  LP = LAGRANGE(DEGREE,DERIV,XI)
  the function determines the values of Lagrange interpolation polynomials of degree DEGREE
  and derivative order DERIV at integration points in vector XI;
  the values are returned in array LP with rows representing the different Lagrange
  polynomials of degree DEGREE and columns representing the values at points XI
  NOTE: XI need to be supplied in the interval -1<xi<1
  EXAMPLE: Lagrange(2,1,xi) returns the first derivative of quadratic Lagrange polynomials at xi

  To go from the interval [-1;+1] to the interval [0;L]:
     Jac = 0.5*L;    xP = Jac.*(1.+xi);
     lp  = lp./(Jac^deriv);

Cross-Reference Information

This function calls:

• Mass4Taper2dFrm_wDF consistent mass matrix for tapered 2d frame element with displ interpolation
• LE2dFrm_w2ndOrdDF 2d LE frame element with moderate deformations under linear or NL geometry
• LE2dFrm_w2ndOrdFF 2d LE frame element with moderate deformations under linear or NL geometry
• LE2dFrm_wVarIDF 2d LE frame element with variable cross section under linear or NL geometry
• LE2dFrm_wVarIFF 2d LE frame element with variable cross section under linear or NL geometry