slepc-3.16.1 2021-11-17
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Sets the parameters defining the ring region.


#include "slepcrg.h" 
PetscErrorCode RGRingSetParameters(RG rg,PetscScalar center,PetscReal radius,PetscReal vscale,PetscReal start_ang,PetscReal end_ang,PetscReal width)
Logically Collective on rg

Input Parameters

rg  - the region context
center  - center of the ellipse
radius  - radius of the ellipse
vscale  - vertical scale of the ellipse
start_ang  - the right-hand side angle
end_ang  - the left-hand side angle
width  - width of the ring

Options Database Keys

-rg_ring_center  - Sets the center
-rg_ring_radius  - Sets the radius
-rg_ring_vscale  - Sets the vertical scale
-rg_ring_startangle  - Sets the right-hand side angle
-rg_ring_endangle  - Sets the left-hand side angle
-rg_ring_width  - Sets the width of the ring


The values of center, radius and vscale have the same meaning as in the ellipse region. The startangle and endangle define the span of the ring (by default it is the whole ring), while the width is the separation between the two concentric ellipses (above and below the radius by width/2).

The start and end angles are expressed as a fraction of the circumference

the allowed range is [0..1], with 0 corresponding to 0 radians, 0.25 to pi/2 radians, and so on. It is allowed to have startangle>endangle, in which case the ring region crosses over the zero angle.

In the case of complex scalars, a complex center can be provided in the command line with [+/-][realnumber][+/-]realnumberi with no spaces, e.g. -rg_ring_center 1.0+2.0i

When PETSc is built with real scalars, the center is restricted to a real value, and the start and end angles must be such that the region is symmetric with respect to the real axis.

See Also


Location: src/sys/classes/rg/impls/ring/rgring.c
Index of all RG routines
Table of Contents for all manual pages
Index of all manual pages