integratePoly

            -->integratePoly

function [iM] = integratePoly(M)

 Integrate each polynomial stored in the matrix M, with respect to
  their (common) variable.
 * M may be an hypermatrix of any dimension.
 * The integration constant is set to zero.
 * Rational fractions are (obviously ;) not supported

 Example:
 M = [ -1+%z 1+2*%z+%z^2 ; 2-%z^3 6]
 integratePoly(M)

 ans  =
            2           2            3  
  - z + 0.5z       z + z + 0.3333333z                                        
              4                         
    2z - 0.25z     6z