06 Tuesday Oct 2009
Tags
arithmetic, bash, bc, calculator, cli
Add the following function to the ~/.bashrc or ~/.bash_aliases, source the former and you’ll get a better command line calculator:
? () { echo "$*" | bc -l; }
You can use it the following way:
$ ? 7*3-5.5
and, no doubt that you’ll get 15.5 as the answer.
N.B. If you use parentheses, you must enclose the whole expression by double quotes.
UPDATE: An alternative way of using bc
$ bc -l <<< "7*3 - 5.5"
17 Thursday Sep 2009
Posted in cli
Tags
bc, calculator, cli, math
Sure, you can use commandline python or ruby (irb); but you may use bc, the inbuilt arbitrary precision calculator, as well. A typical syntax would be:
$ echo "scale=4; 7/9" | bc
where scale=4 tells bc to print the result of 7 divided by 9 with 4 digits after the decimal point.
You may save the following script in a file say cal.bsh in the home directory
#!/bin/bash
echo "scale=4; $1" | bc ;exit
Then make it executable and use it to do the calculation
$ ~/cal.bsh 7/9
For more information: man bc
While you are at it, you may want to have a look at some built-in math functions there, e.g.
s(x) = sin(x)
c(x) = cos(x)
a(x) = arctan(x)
l(x) = Ln(x)
e(x) = exp(x)
These functions are preloaded using the -l flag. Moreover, when this flag is used the default scale is set to 20.
*NIX Tricks 