Writing an integer in an arbitrary base

### 4.4.2 Writing an integer in an arbitrary base

The convert or convertir command does various kinds of conversions depending on the option given as the second argument (see Section 9.2.26).

One thing that convert can do is to convert integers to arbitrary bases and back to the default base, both with the option base.

##### Conversion from base 10.

An integer can be converted into a list of digits in base b by using the convert command.

- convert takes three arguments:
  - n, an integer.
  - base, the symbol verbatim.
  - b, a positive integer, the value of the base.
- convert(n,base,b) returns the list of digits of the integer n when written in base b. The list of digits will start with the 1s term, then the bs term, the b2 term, etc.

#### Examples

convert(123,base,8)

| ⎡ ⎣ | 3,7,1 | ⎤ ⎦

To verify, input 0173 (see Section 4.4.1) or horner(revlist([3,7,1]),8) (see Section 10.1.13 and Section 5.3.14) or convert([3,7,1],base,8) which all return 123.

The base used for convert can be any integer greater than 1. For example, input:

convert(142,base,12)

| ⎡ ⎣ | 10,11 | ⎤ ⎦

##### Conversion from an arbitrary base b.

A number written in base b can be converted into a base 10 integer by using the convert command.

- convert takes three arguments:
  - L, a list of integers representing the digits of the integer in base b, assumed to go in order of increasing significance.
  - base, the symbol verbatim.
  - b, a positive integer, the value of the base.
- convert(L,base,b) returns the integer which, in base b, has the digits given in L.

#### Examples

convert([3,7,1],base,8)

123 |  |  |  |  |  |  |  |  |  |

convert([10,11],base,12)

142 |  |  |  |  |  |  |  |  |  |