How to use the command 'bc' (with examples)

The bc command is an arbitrary precision calculator language that allows users to perform calculations with unlimited precision. It supports a wide range of mathematical functions and can be used interactively or by executing scripts. This article will provide examples of different use cases for the bc command.

Use case 1: Start an interactive session

Code:

bc

Motivation: This use case is useful when you want to perform quick calculations directly in the terminal without having to create a script.

Explanation: Running the bc command without any arguments starts an interactive session. You can then input mathematical expressions directly in the terminal and get the result immediately.

Example output:

scale=20

5 + 3
8

10 * 2
20

sqrt(25)
5

quit

Use case 2: Start an interactive session with the standard math library enabled

Code:

bc --mathlib

Motivation: Enabling the standard math library provides access to additional mathematical functions like sine, cosine, arctangent, natural logarithm, and exponential function.

Explanation: The --mathlib option enables the standard math library of bc. This allows you to use trigonometric functions (s() for sine, c() for cosine, a() for arctangent), logarithmic functions (l() for natural logarithm), and the exponentiation function (e()).

Example output:

scale=10

s(0)
.0000000000

c(0)
1

a(0)
.0000000000

l(10)
2.3025850930

e(1)
2.7182818284

quit

Use case 3: Calculate an expression

Code:

bc --expression='5 / 3'

Motivation: This use case is suitable when you need to calculate a single mathematical expression without entering an interactive session.

Explanation: The --expression option allows you to directly specify a mathematical expression to be evaluated. In this example, the expression 5 / 3 will be calculated.

Example output:

1

Use case 4: Execute a script

Code:

bc path/to/script.bc

Motivation: When you have a script with multiple mathematical calculations, you can execute it using the bc command.

Explanation: In this use case, the bc command is followed by the path to a script file (e.g., path/to/script.bc). The file contains a series of mathematical expressions that will be evaluated in order.

Example output (contents of script.bc):

scale=5

5 + 3

Use case 5: Calculate an expression with the specified scale

Code:

bc --expression='scale = 10; 5 / 3'

Motivation: The scale determines the number of decimal places that will be displayed in the calculation result. This use case is helpful when you want to specify a custom scale for a specific calculation.

Explanation: By including scale = 10; before the expression, you are setting the scale to 10 decimal places. In this example, the expression is 5 / 3, but the result will be displayed with 10 decimal places.

Example output:

1.6666666667

Use case 6: Calculate a sine/cosine/arctangent/natural logarithm/exponential function using mathlib

Code:

bc --mathlib --expression='s(1)'

Motivation: This use case is useful when you want to calculate a specific mathematical function using the mathlib enabled.

Explanation: The --mathlib option enables the standard math library, as described in use case 2. By specifying s(1) as the expression, you are calculating the sine of 1.

Example output:

.8414709848

Conclusion:

The bc command is a powerful calculator language that allows for precise mathematical calculations. From starting interactive sessions to executing scripts and calculating various mathematical functions, the bc command provides a versatile tool for mathematical calculations.