ptrend — matrix of polynomial trend
[xmat]=ptrend(p,nobs)
p = order of the time-trend polynomial
* p < 0, xmat = empty vector
* p = 1, xmat = time trend
* p > 1, xmat = higher order polynomial in time
nobs = size of the matrix
xmat = matrix containing polynomial trend model data set
1) ext=ptrend(2,10) 2) r=ols1(y,ptrend(t,nobs)) Example 1 gives the matrix: ! 1. 1. 1. ! ! 1. 2. 4. ! ! 1. 3. 9. ! ! 1. 4. 16. ! ! 1. 5. 25. ! ! 1. 6. 36. ! ! 1. 7. 49. ! ! 1. 8. 64. ! ! 1. 9. 81. ! ! 1. 10. 100. ! In example 2 (taken from kpss) ptrend calculates the matrix of trends corresponding to the choice of the user for t and the # of observations nobs of the variable y and enter them in the function ols1.