### astZoomMap

Create a ZoomMap

#### Description:

This function creates a new ZoomMap and optionally initialises its attributes.

A ZoomMap is a Mapping which " zooms" a set of points about the origin by multiplying all coordinate values by the same scale factor (the inverse transformation is performed by dividing by this scale factor).

#### Synopsis

AstZoomMap $\ast$astZoomMap( int ncoord, double zoom, const char $\ast$options, ... )

#### Parameters:

##### ncoord
The number of coordinate values for each point to be transformed (i.e. the number of dimensions of the space in which the points will reside). The same number is applicable to both input and output points.
##### zoom
Initial scale factor by which coordinate values should be multiplied (by the forward transformation) or divided (by the inverse transformation). This factor may subsequently be changed via the ZoomMap’ s Zoom attribute. It may be positive or negative, but should not be zero.
##### options
Pointer to a null-terminated string containing an optional comma-separated list of attribute assignments to be used for initialising the new ZoomMap. The syntax used is identical to that for the astSet function and may include " printf" format specifiers identified by " %" symbols in the normal way.
##### ...
If the " options" string contains " %" format specifiers, then an optional list of additional arguments may follow it in order to supply values to be substituted for these specifiers. The rules for supplying these are identical to those for the astSet function (and for the C " printf" function).

#### Returned Value

##### astZoomMap()
A pointer to the new ZoomMap.

#### Notes:

• A null Object pointer (AST__NULL) will be returned if this function is invoked with the AST error status set, or if it should fail for any reason.

#### Status Handling

The protected interface to this function includes an extra parameter at the end of the parameter list descirbed above. This parameter is a pointer to the integer inherited status variable: " int $\ast$status" .