calculate a+b or a*b instantly on the command line or in a batch file with sfk calc for Windows, Mac OS X and Linux.

sfk calc "1+2*3"

do a simple calculation with mathematical
operators + - * /

options
-dig[its]=n  round result to n digits
-form        also print the formula,
tab separated after result
-sum         add values from chain text

experimental brackets support
you may add option -bra[ckets] to use formulas
with brackets, like
sfk calc -bra 1.0/(1.0-1.0/(3+5)*9)
however this is an experimental feature.
wrong calculations may occur with brackets,
on highly complex formulas. therefore:
- counter-check the output with an alternate
calculator before using a command repeatedly.
- if you really find formulas that calculate
wrong, supply samples in the sfk forum.

chaining support
can use chain input data as #text within formula.

web reference
http://stahlworks.com/sfk-calc

examples
sfk calc "1.0+2.5*3.5"
prints 9.75. quotes "" are required
with linux but not under windows.
sfk echo "1+2*3" +calc "#text*4"
calculates 1 + 2*3*4 = 25
sfk echo "1+2*3" +calc "#text" +calc "#text*4"
calculates (1+2*3) * 4 = 28
sfk filt in.txt +calc "#text" -form
calculate all formulas given in in.txt
sfk list -size -tabform sfk.exe +filt -utabform "#col1"
+calc "#text/1000" -dig=0
show the size of sfk.exe in kbytes, rounded to
zero digits after decimal point.  
sfk filt in.csv -utabform "#col2" +calc -sum -dig=2
if in.csv contains two tab-separated columns like
apple	1.00
banana	1.50
pineapple	2.50
then add prices from the second column.