[donev@pc346g-02 solutions]$ f90-vast worksheet4.f90 -o worksheet4.x worksheet3.o worksheet3.alternative.o
 Pacific-Sierra Research vf90 Personal   V3.4N5 15:00:46  12/ 7/00   f90 to f77  
    program    erf_file                        
 Warning, line 24: 
    I/O keyword could not be translated into FORTRAN 77. (ACTION)
 Warning, line 24: Specifier removed, but may not yield same results. (ACTION)
[donev@pc346g-02 solutions]$ worksheet4.x
Enter: epsilon, n_points, x_min and x_max: 1E-6,5,0.0,4.5
[donev@pc346g-02 solutions]$ more Erf.dat
  0.  0.
  1.125  0.888388157
  2.25  0.998537421
  3.375  0.999912143
  4.5  0.831478536
[donev@pc346g-02 solutions]$ worksheet4.x
Enter: epsilon, n_points, x_min and x_max: 1E-6,100,0.0,4.5
[donev@pc346g-02 solutions]$ xmgrace Erf.dat &
[3] 14534
[donev@pc346g-02 solutions]$