#!/bin/bash
# Desc: Sums newline-delimited floats received from stdin
# Usage: some_app | sumFloat
# Example: printf -- "-3\n0.14" | sumFloat
#   Result: -2.860000
# Version: 0.0.2
# Depends: bc 1.07.1

yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
dief() { yell "$*"; return 111; } # same as yell() but non-zero return status
must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails
sum_float() {
    # Desc: Sums newline-delimited floats received on stdin
    # Usage: some_app | sum_float
    # Depends: bc 1.07.1, paste (GNU coreutils)

    # Check dependencies
    command -v bc 1>/dev/random 2>&1 || { dief "FATAL:Missing:bc"; };
    [[ ! -t 0 ]] || { dief "FATAL:No stdin detected."; };

    # Process lines
    local line re; local -a nums=();
    re='^[+-]?([0-9]+([.][0-9]*)?|[.][0-9]+)$';
    while IFS= read -r line; do
        [[ -z $line ]] && continue;
        [[ $line =~ $re ]] || { dief "FATAL:Not a float:${line}"; };
        nums+=("$line");
    done;

    # Print output
    if (( ${#nums[@]} == 0 )); then printf '0.000000\n'; return 0; fi;
    LC_ALL=C printf '%.6f\n' "$(printf '%s\n' "${nums[@]}" | paste -sd+ - | bc -l)";
} # sum stdin floats

# Author: Steven Baltakatei Sandoval
# License: GPLv3+