#!/usr/bin/perl -w

# ================================================================
# This program evaluates a user-specified function on m = 0, 1, ..., mmax,
# and also computes partial sums.
#
# Example:
#
# sumupx  10 "2*m+1" | colprint -r
#   m 2*m+1   sum
# --- ----- -----
#   0     1     1
#   1     3     4
#   2     5     9
#   3     7    16
#   4     9    25
#   5    11    36
#   6    13    49
#   7    15    64
#   8    17    81
#   9    19   100
#  10    21   121
#
# Another example:
#
# sumupx  10 "m*(m+1)/2" | colprint -r
#   m  m*(m+1)/2   sum
# ---  --------- -----
#   0          0     0
#   1          1     1
#   2          3     4
#   3          6    10
#   4         10    20
#   5         15    35
#   6         21    56
#   7         28    84
#   8         36   120
#   9         45   165
#  10         55   220
#
# ================================================================
# John Kerl
# kerl.john.r@gmail.com
# 2005-06-18
# ================================================================


die "Usage: $0 {m max} {expression in m}\n" unless @ARGV == 2;

$mmax = shift @ARGV;
$orig_expr = shift @ARGV;
$eval_expr = $orig_expr;
$eval_expr =~ s/m/\$m/g;

print "m $orig_expr sum\n";
print "--- ", "-" x length($orig_expr), " -----\n";
$sum = 0;
for ($m = 0; $m <= $mmax; $m++) {
	$y = eval($eval_expr);
	$sum += $y;
	print "$m $y $sum\n";
}