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--- bash_functions [2014/08/05 18:49] – [Print lines on screen descending from the current point] k2patel
+++ bash_functions [2014/09/29 01:25] – [Integer or Decimal] k2patel
@@ Line 225: / Line 225: @@
 [[ https://www.linkedin.com/groups/How-can-i-verify-if-3716796.S.5862974732210556931?view=&item=5862974732210556931&type=member&gid=3716796&trk=eml-b2_anet_digest-null-2-null&fromEmail=fromEmail&ut=3KLlfwU1D4UCk1 | From Article ]]
+==== floating point multiplication ====
+<code bash>
+fpmul() #@ Perform floating-point multiplication in the shell
+{ #@ USAGE: fpmul [VAR] NUM.DEC ...
+local _var= _places _tot _neg _n _int _dec _df _fpmul
+if [[ ${1^^} =~ ^[A-Z_][A-Z0-9_]*$ ]]
+then
+_var=$1
+shift
+fi
+_places=
+_tot=1
+_neg=
+for _n
+do
+## 2 negatives make a positive
+case $_n in
+-*) [ "$_neg" = '-' ] && _neg= || _neg='-'
+_n=${_n#-}
+;;
+esac
+## Check for non-numeric characters
+case $_n in
+*[!0-9.]*) return 1 ;;
+esac
+## count the number of decimal _places,
+## then remove the decimal point
+case $_n in
+.*) _int=
+_dec=${_n#?}
+_places=$_places$_dec
+_n=$_dec
+;;
+*.*) _dec=${_n#*.}
+_int=${_n%.*}
+_places=$_places$_dec
+_n=$_int$_dec
+;;
+esac
+## remove leading zeroes
+while :
+do
+case $_n in
+""|0) _n=0
+_fpmul=0
+return
+;;
+*) _n=${_n#0} ;;
+*) break;;
+esac
+done
+## multiply by the previous _total
+_tot=$(( $_tot * ${_n:-0} ))
+## report any overflow error
+case $_tot in
+-*) printf "fpmul: overflow error: %s\n" "$_tot" >&2
+return 1
+;;
+esac
+done
+while [ ${#_tot} -lt ${#_places} ]
+do
+_tot=0$_tot
+done
+_df=
+while [ ${#_df} -lt ${#_places} ]
+do
+left=${_tot%?}
+_df=${_tot#$left}$_df
+_tot=$left
+done
+_fpmul=$_tot${_df:+.$_df}
+## remove trailing zeroes or decimal points
+while :
+do
+case $_fpmul in
+*.*[0\ ]|*.) _fpmul=${_fpmul%?} ;;
+.*) _fpmul=0$_fpmul ;;
+*) break ;;
+esac
+done
+[[ $_var ]] &&
+printf -v "$_var" %s "$_fpmul" ||
+printf '%s\n' "$_fpmul"
+}
+num.dec
+</code>
+[[http://www.linkedin.com/groups/Fridays-function-fpmul-Perform-floatingpoint-3716796.S.5921339472191987716?view=&item=5921339472191987716&type=member&gid=3716796&trk=eml-b2_anet_digest-hero-1-hero-disc-disc-0&midToken=AQG8JYIVdmXjvA&fromEmail=fromEmail&ut=3_RJ7vAOch56s1|From article]]