def updateEvolution(self):
        '''
        Updates the "population punk proportion" evolution array.  Fasion victims
        believe that the proportion of punks in the subsequent period is a linear
        function of the proportion of punks this period, subject to a uniform
        shock.  Given attributes of self pNextIntercept, pNextSlope, pNextCount,
        pNextWidth, and pGrid, this method generates a new array for the attri-
        bute pEvolution, representing a discrete approximation of next period
        states for each current period state in pGrid.

        Parameters
        ----------
        none

        Returns
        -------
        none
        '''
        self.pEvolution = np.zeros((self.pCount,self.pNextCount))
        for j in range(self.pCount):
            pNow = self.pGrid[j]
            pNextMean = self.pNextIntercept + self.pNextSlope*pNow
            dist = approxUniform(N=self.pNextCount,bot=pNextMean-self.pNextWidth,top=pNextMean+self.pNextWidth)[1]
            self.pEvolution[j,:] = dist
Updates the "population punk proportion" evolution array.  Fasion victims
        believe that the proportion of punks in the subsequent period is a linear
        function of the proportion of punks this period, subject to a uniform
        shock.  Given attributes of self pNextIntercept, pNextSlope, pNextCount,
        pNextWidth, and pGrid, this method generates a new array for the attri-
        bute pEvolution, representing a discrete approximation of next period
        states for each current period state in pGrid.

        Parameters
        ----------
        none

        Returns
        -------
        none