Bash Arithmetic

Another possible solution is to add a simple function for Bash's built-in arithmetic. Put this in your .bashrc file to try it out:

=() {

    echo "$(($@))"

}

So now, you don't even need $((...)) anymore, just = which seems natural enough.

Replacement

Another thing if you want to be even faster: you can make it replace p with + and x with *. This will work for that:

=() {

    local IFS=' '

    local calc="${*//p/+}"

    calc="${calc//x/*}"

    echo "$(($calc))"

}



= 5 x 5  # Returns 25

= 50p25  # Returns 75

Now you don't even need Shift anymore, the only thing is =  in front of arithmetic.

Hexadecimal output

Output can be displayed in both decimal and hexadecimal, if so desired. (Note: using x substitution will conflict with the 0x... hex syntax)

=() {

    local answer="$(($@))"

    printf '%d (%#x)

' "$answer" "$answer"

}

Example:

$ = 16 + 0x10

272 (0x110)



$ = 16**3 + 16**4

69632 (0x11000)

Using bc

If you want slightly more advanced calculations, you can pipe it to bc like so:

=() {

    local IFS=' '

    local calc="${*//p/+}"

    calc="${calc//x/*}"

    bc -l <<<"scale=10;$calc"

}



= 'sqrt(2)' # Returns 1.4142135623

= '4*a(1)'  # Returns pi (3.1415926532)

The functions provided by bc are as follows (and can be found in man bc):

sqrt ( expression )

       The value of the sqrt function is the square root of the expression.  

       If the expression is negative, a run time error is generated.



s (x)  The sine of x, x is in radians.



c (x)  The cosine of x, x is in radians.



a (x)  The arctangent of x, arctangent returns radians.



l (x)  The natural logarithm of x.



e (x)  The exponential function of raising e to the value x.



j (n,x)

       The Bessel function of integer order n of x.

It also supports if, for, while, and variables like a programming language. Though it may be better to write to a file if you wanted that.

Keep in mind that it will substitute p and x in function/variable names. It may be better to just remove the replacements.

Using gcalccmd

You can also make the function call gcalccmd (from gnome-calculator) like so:

=() {

    local IFS=' '

    local calc="$*"

    # Uncomment the below for (p → +) and (x → *)

    #calc="${calc//p/+}"

    #calc="${calc//x/*}"

    printf '%s

 quit' "$calc" | gcalccmd | sed 's:^> ::g'

}



= 'sqrt(2)' # Returns 1.4142135623

= '4^4'     # Returns 256

The available functions seem to be (taken straight from the source code), == denotes equivalent functions:

ln()

sqrt()

abs()

int()

frac()

sin()

cos()

tan()

sin⁻¹() == asin()

cos⁻¹() == acos()

tan⁻¹() == atan()

sinh()

cosh()

tanh()

sinh⁻¹() == asinh()

cosh⁻¹() == acosh()

tanh⁻¹() == atanh()

ones()

twos()