php examples  that run in command line and on web
   datatypes.php 
   operators.php 
   loop.php 
   foreach.php 
   while.php 
   do_while.php 
   ifelse.php 
   function.php 
   math.php 
   array.php 
   array2.php 
   crossprod.php 
   test_matrix.php  uses  matrix.php
   test_deriv.php  uses  deriv.php
   pde22_eq.php  uses matrix.php deriv.php
   readfile.php 
   date_time.php 
   comment.php 

  copy source code from /afs/umbc.edu/users/s/q/squire/pub/www/