Next  |  Prev  |  Up  |  Top  |  Index  |  JOS Index  |  JOS Pubs  |  JOS Home  |  Search

## Complex Numbers in Matlab and Octave

Matlab and Octave have the following primitives for complex numbers:

```octave:1> help j

j is a built-in constant

- Built-in Variable: I
- Built-in Variable: J
- Built-in Variable: i
- Built-in Variable: j

A pure imaginary number, defined as `sqrt (-1)'.  The `I' and `J'
forms are true constants, and cannot be modified.  The `i' and `j'
forms are like ordinary variables, and may be used for other
purposes.  However, unlike other variables, they once again assume
their special predefined values if they are cleared *Note Status
of Variables::.

Additional help for built-in functions, operators, and variables
is available in the on-line version of the manual.  Use the command
`help -i <topic>' to search the manual index.

Help and information about Octave is also available on the WWW
at http://www.octave.org and via the help-octave@bevo.che.wisc.edu
mailing list.

octave:2> sqrt(-1)
ans = 0 + 1i

octave:3> help real
real is a built-in mapper function

- Mapping Function:  real (Z)
Return the real part of Z.

octave:4> help imag
imag is a built-in mapper function

- Mapping Function:  imag (Z)
Return the imaginary part of Z as a real number.

octave:5> help conj
conj is a built-in mapper function

- Mapping Function:  conj (Z)
Return the complex conjugate of Z, defined as
`conj (Z)' = X - IY.

octave:6> help abs
abs is a built-in mapper function

- Mapping Function:  abs (Z)
Compute the magnitude of Z, defined as
|Z| = `sqrt (x^2 + y^2)'.

For example,

abs (3 + 4i)
=> 5
...
```
```octave:7> help angle
angle is a built-in mapper function

- Mapping Function:  angle (Z)
See arg.
...
```