# ncl_ngritd (3) - Linux Manuals

## ncl_ngritd: Given the coordinates of a point, this routine performs a rotation

## NAME

NGRITD - Given the coordinates of a point, this routine performs a rotation of that point about a specified axis by a specified angle.

## SYNOPSIS

CALL NGRITD (IAXS,ANGL,UCRD,VCRD,WCRD)## C-BINDING SYNOPSIS

#include <ncarg/ncargC.h>
void c_ngritd(int iaxs, float angl, float *ucrd, float *ycrd,

float *wcrd)

## DESCRIPTION

- IAXS
- (an input expression of type INTEGER) specifies the axis about which rotation is to be done (1 for the U axis, 2 for the V axis, and 3 for the W axis).
- ANGL
- (an input expression of type REAL) specifies the magnitude, in degrees, of the rotation angle.
- UCRD
- (an input/output variable of type REAL) specifies the U coordinate of the point being rotated.
- VCRD
- (an input/output variable of type REAL) specifies the V coordinate of the point being rotated.
- WCRD
- (an input/output variable of type REAL) specifies the W coordinate of the point being rotated.

## C-BINDING DESCRIPTION

The C binding argument descriptions are the same as the FORTRAN argument descriptions.## USAGE

This routine is used by NGGCOG and NGGSOG to effect the rotations that are used to generate an object of a specified shape at a specified point on the surface of the globe.NGRITD assumes that the UVW coordinate system is right-handed. Positive values of ANGL give counter-clockwise rotations and negative values of ANGL give clockwise rotations. (When IAXS = 1, ANGL = 90 carries the positive V axis into the positive W axis; when IAXS = 2, ANGL = 90 carries the positive W axis into the positive U axis; when IAXS = 3, ANGL = 90 carries the positive U axis into the positive V axis.)

## EXAMPLES

Use the ncargex command to see the following relevant example: cpex10.

## ACCESS

To use NGRITD or c_ngritd, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c, preferably in that order.## MESSAGES

None.## COPYRIGHT

Copyright (C) 1987-2009University Corporation for Atmospheric Research

The use of this Software is governed by a License Agreement.