Task

Write two equal-sized numerical arrays 'x' and 'y' to
a two-column text file named 'filename'.

The first column of the file contains values from an 'x'-array with a
given 'xprecision', the second -- values from 'y'-array with 'yprecision'.

For example, considering:

   x = {1, 2, 3, 1e11};
   y = {1, 1.4142135623730951, 1.7320508075688772, 316227.76601683791}; 
                                                          /* sqrt(x) */
   xprecision = 3;
   yprecision = 5;

The file should look like:

   1    1
   2    1.4142
   3    1.7321
   1e+011   3.1623e+005

This task is intended as a subtask for Measure relative performance of sorting algorithms implementations.




(with-open-file (stream (make-pathname :name "filename") :direction :output)
    (let* ((x (make-array 4 :initial-contents '(1 2 3 1e11)))
              (y (map 'vector 'sqrt x))
              (xprecision 3)
              (yprecision 5)
              (fmt (format nil "~~,1,~d,,G~~12t~~,~dG~~%" xprecision yprecision)))
        (map nil (lambda (a b)
                     (format stream fmt a b)) x y)))