functions:INTEGRAL

example

 Suppose you need the integral, from 0 to pi, of cos(x)^3+sin(x)^4
 The following commands could be used:

  X = [0:PI:.1]
  YI = (INTEGRAL(X,COS(X)^3+SIN(X)^4))[LEN(X)]

SMOOTH

 syntax: INTEGRAL( x,y )
         INTEGRAL( x,y,`SMOOTH' )

 This method utilizes an interpolating spline under tension. The
 spline tension used is the current value of TENSION, which may be
 changed with the SET command. The nature of the interpolating curve
 varies continuously from pure cubic spline, for TENSION = 0, to a
 piecewise linear curve, that is, points joined by straight line
 segments, for large TENSION.