# Difference between revisions of "Octave Basics"

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For the meaning of operators, see the GNU Octave manual.

## Contents

### The very basics

`+` , `-` , `*` , `/` , `^` , `pi` , `I` , `e` , `inf` , `eps` , `sin` , `cos` , `tan` , `exp` , `log` , `log10` , `abs` , `sqrt` , `sign` , `round` , `ceil` , `floor` , `fix` , `=` , `,` , `;` , `who` , `clear` , `help` , `lookfor`

```x = pi, y = floor (sin (x)), z = log (exp (2013)), z / inf
```

### Vectors and matrices

`:` , `.*` , `./` , `.^` , `'` , `.'` , `\` , `length` , `numel` , `size` , `zeros` , `ones` , `eye` , `diag` , `rand` , `det` , `trace` , `inv` , `lu` , `eig` , `cond` , `expm`

``` x = 1:5, x(:), x(2:4), A = [11 12; 21, 22], A(1,1:end) ↵
```

### Graphics

plot | semilogx | semilogy | loglog | contour | quiver | surf | mesh | meshgrid | xlabel | ylabel | zlabel | title | grid | axis | hold | subplot | figure | print

```t = 0:0.01*pi:21*pi; x = sin (t).*(exp (cos (t)) - 2*cos (4*t) + sin (t/12).^5); y = cos (t).*(exp (cos (t)) - 2*cos (4*t) + sin (t/12).^5); plot(x, y) ↵
```

### Scripts and functions

@ | function | return | nargin | nargout | varargin | varargout | feval | eval

```f = @(x) x.^2, f(1:10) ↵
```
```function v = cossum (x, n) v = cumsum (repmat (cos (x), 1, n));
```

### Programming elements

== | > | < | >= | <= | != | | || | | & | && | ! | if | else | elseif | for | while |end | break | continue | pause

```for i = 1:5 if (i < 3) disp (i) else disp (i^2) end end ↵
```