# NhlNDCToData (ndctodata)

Converts NDC units into data coordinates. (See
NhlNDCToData.)
Two names are
provided for this NCL procedure: the formal name is NhlNDCToData, and the
abbreviated name is ndctodata.

## Synopsis

procedure NhlNDCToData(
plot[1] : graphic,
x_in[*] : float,
y_in[*] : float,
x_out[*] : float,
y_out[*] : float
)
or
procedure ndctodata(
plot[1] : graphic,
x_in[*] : float,
y_in[*] : float,
x_out[*] : float,
y_out[*] : float
)

## Arguments

*plot*
Instance of an HLU plot.
*x_in*
Single-dimensioned floating-point vector of x NDC units.
*y_in*
Single-dimensioned floating-point vector of y NDC units; must be
the same size as *x_in*.
*x_out*
Single-dimensioned floating-point vector the same size as *x_in*;
will contain x-coordinate output for **NhlNDCToData**.
*y_out*
Single-dimensioned floating-point vector the same size as *x_out*;
will contain y-coordinate output from **NhlNDCToData**.

## Description

The **NhlNDCToData** procedure uses the built-in
transformation mapping feature of HLU plot objects to map NDC
coordinates into data coordinates.
All four floating-point parameters must
have the same number of elements. **NhlNDCToData** maps coordinate
pairs from *x_in* and *y_in* and places the results in the
corresponding elements of *x_out* and *y_out*, respectively.
Both *x_out* and *y_out* can be the same variables as
*x_in* and *y_in*. When the data coordinates are outside
the NDC viewport specified in the plot, a missing value is placed in
both of the corresponding indexes in the output arrays. The missing value
chosen is either the *x_in* missing value, *y_in* missing value,
or a system default.

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* $Revision: 1.11 $ $Date: 1998/09/17 16:10:46 $ *