LINUX arbitrary precision Calculator BC usage __linux

"Purpose description"
Bash has built-in support for integer arithmetic, but does not support floating-point operations, and the BC Command makes it easy to do floating-point operations, and of course integer operations are no longer spoken. The man page says that BC is an arbitrary precision calculator language, a computational language of arbitrary precision, a language that provides some grammatical structures, such as conditional judgments, loops, and so on, which can be said to be very powerful, But I haven't found the occasion to use it in practice. Another use is to make a conversion.
"Common parameters"
In general, we use the BC command without any parameters:
Bc
If you need the BC do not output prompt information, you can add the-Q parameter:
Bc-q
If you want to use a powerful math library, such as trigonometric functions, you need to add the-l parameter:
Bc-l
Because BC itself is a command interpreter, to exit it simply enter quit carriage return or press Ctrl+d to terminate.
"Use Example"
Example one command line using BC
[Root@localhost centos39]# BC
BC 1.06
Copyright 1991-1994, 1997, 1998, Free Software Foundation, Inc.
This are free software with absolutely NO WARRANTY.
For details type ' warranty '.
3+4
7
3-4
-1
3*4
12
3/4
0
SCALE=2;3/4 # Keep The decimal point precision is valid only for division, fetch, and power
.75
3/4
.75
3%4
0
Scale=0
3%4
3
3^4
81
Ctrl+d
[Root@localhost centos39]#
Example two uses the BC to calculate through the pipeline
[Root@localhost centos39]# Echo 3 * 4 | Bc
(standard_in) 1:parse error
[Root@localhost centos39]# echo "3 * 4" | Bc
12
[Root@localhost centos39]# echo "scale=7; 355/113 "| Bc
3.1415929

[Root@localhost centos39]#

In this way, you can also use the size comparison of floating-point data types:

a=1.2

b=3.2

C= ' echo ' $a < $b | BC '

echo "$c"

The above script execution result is 1, and if the result of the comparison is not satisfied (for example, change the above $a < $b to $a > $b), the output result is 0.

Note: It must be noted here that this comparison result is 0 or 1, rather than representing true or false, and therefore cannot be used for conditional judgment after if. Remember to remember.

Sample Triple Conversion
[Root@rhel55 ~]# echo "IBASE=16; FFFF "| Bc
65535
[Root@rhel55 ~]# echo "OBASE=16; 1000 "| Bc
3E8
[Root@rhel55 ~]#


We use the IBase and Obase methods of BC.

IBase is the input of a number, and the obase is the output of the number of the system. Well remember, I am input,o is output.

If you use a command to turn a number, you can use the echo command and the pipe to combine the BC. As follows:

10-in-turn 2-in-system:

$ echo "obase=2;ibase=10;100" | bc1100100

10-in-turn 16-in-system:

$ echo "obase=16;ibase=10;100" | Bc64

16-in-turn 10-in-system:

$ echo "ibase=16;obase=2; F1 "| bc11110001

Note that the F of the 16 binary number is capitalized, if the lowercase result is incorrect. As the top is not specified, the default is 10.
example four writes multiple expressions in a file to calculate together
[Root@rhel55 ~]# Cat TEST.BC
123*321
123/321
scale=4;123/321

[Root@rhel55 ~]# BC TEST.BC
BC 1.06
Copyright 1991-1994, 1997, 1998, Free Software Foundation, Inc.
This are free software with absolutely NO WARRANTY.
For details type ' warranty '.
39483
0
.3831
Ctrl+d
[Root@rhel55 ~]#
[Root@rhel55 ~]# Cat TEST.BC | Bc
39483
0
.3831
[Root@rhel55 ~]#
Example 51 bash script for calculating Triangle area
First, review the knowledge of Junior high School: B means the bottom of the triangle, H is the height of the triangle, then the area of the Triangle calculation formula is B*H/2.

File: area_of_triangle.sh
Bash code
#!/bin/bash

# Shell Program/script to read the base and height of a traingle
# -------------------------------------------------------------------------
# Copyright (c) Nixcraft project # This script is licensed under GNU GPL version 2.0 or above
# -------------------------------------------------------------------------
# This script are part of Nixcraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/for more information.
# -------------------------------------------------------------------------
# Formula Info:http://www.mste.uiuc.edu/dildine/heron/triarea.html
# area= (1/2) x Base x Height

Echo-n "Enter base of a triangle:"
Read B

Echo-n "Enter the height of a triangle:"
Read H

# Calculate it and display back
Area=$ (echo "scale=2" (1/2) * $b * $h "|BC)
echo "Area of a triangle is $area"


[ROOT@SMSGW academic]#./area_of_triangle.sh
Enter base of a triangle:123
Enter height of a triangle:321
Area of a triangle is 19741.50
[ROOT@SMSGW academic]#
example six script fragment using the BC command
Bash code
# usage:calc_sum <num1> <num2>
# calculates the number of two and
Calc_sum ()
{
Bc-q <<eof
$1+$2
Eof
}

# Usage:calc_free <count>
# 0.05 yuan for cost calculation
Calc_fee ()
{
Bc-q <<eof
0.05*$1
Eof
}


Paste the above code to the terminal.
[Root@web ~]# # usage:calc_sum <num1> <num2>
[Root@web ~]# # calculates two numbers and
[Root@web ~]# Calc_sum ()
> {
> Bc-q <<eof
> $1+$2
> EOF
>}
[Root@web ~]#
[Root@web ~]# # Usage:calc_free <count>
[Root@web ~]# # 0.05 yuan per unit cost
[Root@web ~]# Calc_fee ()
> {
> Bc-q <<eof
> 0.05*$1
> EOF
>}
[Root@web ~]#
[Root@web ~]#
[Root@web ~]# calc_sum 123 321
444
[Root@web ~]# Calc_fee 1000
50.00
[Root@web ~]#
example seven uses the math library
It is said that the PI value of 100 digits can be calculated.
[Root@web ~]# echo "SCALE=100; A (1) *4 "| Bc
Runtime error (func= (main), adr=11): Function a not defined.
[Root@web ~]# echo "SCALE=100; A (1) *4 "| Bc-l
3.141592653589793238462643383279502884197169399375105820974944592307\
8164062862089986280348253421170676
[Root@web ~]#