How to perform mathematical operations on linux terminal?

pratikjajal · 01-02-2014, 11:35 PM

Dear All,

Following is the command which is used to perform the mathematical operations on terminal:

Command:
echo "10.25*12" | bc -l

The answer will be 123.00 for the above mentioned command.

With the minor change in echo "Write here any mathematical operation", we can perform any mathematical operation.

Examples:
echo "25-12" | bc -l
echo "25+12" | bc -l
echo "25*12" | bc -l
echo "25/12" | bc -l
echo "25%12" | bc -l

If you need more help, please put your questions herewith this post.If you know more things about this share your ideas with me.

Regards,
Pratik

anon237 · 01-03-2014, 03:26 AM

In addition to the above, here are some bc related links that might come in handy:
- command-line calculations using bc
- Linux and Unix bc command

And two of my blog entries:
- Convert numeral systems
- Convert Metric <-> Imperial

j-ray · 01-03-2014, 03:41 AM

Another option:

perl -e "print sqrt(20736)";
perl -e "print 12**2"

Or use python as a calculator

python // open python prompt
import math // import math module
math.sqrt(144) // do your calculations...

(leave the prompt with ctrl-D)

Soderlund · 01-03-2014, 04:37 AM

Quote:

Originally Posted by druuna

command-line calculations using bc

Interesting. I see you can also run it like a script instead of using bc files (though I don't know if it's any useful):

Code:

#!/usr/bin/bc -q
ibase=10
obase=2
for (;;)
{
        print "Decimal (0 to stop): "
        x = read()
        if (0 == read)
        {
                break;
        }
        print "Binary: "
        x
}
quit

anon237 · 01-03-2014, 05:26 AM

@Soderlund: bc is a powerful tool which is often used in a simple form (echo some arithmetic operations and pipe it to bc).

I do see the usefulness of bc scripts, but I also tend to use echo to pipe it to bc, especially if the arithmetic that needs to be done is "simple".

I have this bash function in place:

Code:

# Function : cmToFi 
# Syntax   : cmToFi <centimeters> 
# 
# Convert centimeters to feet and inches 
function cmToFi() { 
  FEET=$( echo "scale=0;($1 * 0.3937) / 12" | bc ) 
  FEETTOT=$( echo "scale=2;($1 * 0.3937) / 12" | bc ) 
  INCHES=$( echo "scale=0;(($FEETTOT - $FEET) * 12 + 0.5)/1" | bc ) 
  echo "$FEET $INCHES" 
}

which could be rewritten as:

Code:

#!/usr/bin/bc -q

onefeet=0.3937

print "\nConvert centimeters to feet and inches\n"
print "- Centimeters: " ; cmin=read()

scale=0
xfeet=(cmin * onefeet)/12
scale=2
totfeet=(cmin * onefeet)/12
scale=0
xinches=((totfeet - xfeet) * 12 + 0.5)/1

print cmin
print " centimeters equals "
print xfeet
print " feet and "
print xinches
print " inches"
print "\n"
quit

If the arithmetic gets complicated it is probably better to use a bc script instead of echoing multiple statements to bc.

BTW: There's a typo in your example:

Code:

        x = read()
        if (0 == read)
        {

That should be:

Code:

        x = read()
        if (0 == x)
        {

patrick295767 · 01-25-2014, 03:03 AM

You could use the bash simply:
e=$(($i +1)) /sthg like this

or a C program that allows you to do any mathematical operation. C is surely the best rather than use slow, buggy, python. Perl is probably on your distro, python maybe not. gcc is the core of Linux, so I recommend C or C++

anon237 · 01-25-2014, 03:12 AM

Quote:

Originally Posted by patrick295767

You could use the bash simply:
e=$(($i +1)) /sthg like this

That won't work.

The syntax is wrong and more importantly: Bash doesn't handle floating point very well, you'll end up with a rounded integer.

patrick295767 · 01-25-2014, 04:24 AM

Quote:

Originally Posted by druuna

That won't work.

The syntax is wrong and more importantly: Bash doesn't handle floating point very well, you'll end up with a rounded integer.

Oh, man. This might be true. I forgot it, I dont use bash on regular basis any longer.

ok so it might be

Code:

#include <stdio.h>
#include <unistd.h>
#include <math.h>
#include <string.h> // for strncpy  

// simple math calc: gcc -lm math.c  -o test-bin

int main(){
  printf(" Hello: %g \n" , 12 * 3.4 );
  return 0;
}

I include more in case you do slightly more stuffs.

NeXuS_2006 · 01-26-2014, 09:55 PM

You'd rather write a C program, compile, and run it than use "slow, buggy python"?