Struct Beam 

pub struct Beam {
    pub major_deg: f64,
    pub minor_deg: f64,
    pub pa_deg: f64,
}

A 2D elliptical Gaussian beam in FITS conventions.

Examples

use convolve_rs::Beam;

let beam = Beam::from_arcsec(20.0, 10.0, 45.0)?;
assert_eq!(beam.major_arcsec(), 20.0);
assert_eq!(beam.major_deg, 20.0 / 3600.0);

Fields

major_deg: f64

FWHM major axis in degrees (FITS BMAJ)

minor_deg: f64

FWHM minor axis in degrees (FITS BMIN)

pa_deg: f64

Position angle in degrees East of North (FITS BPA)

Implementations

impl Beam

pub fn new( major_deg: f64, minor_deg: f64, pa_deg: f64, ) -> Result<Self, BeamError>

Create a beam from FWHM axes in degrees and a position angle in degrees East of North.

Errors

Returns BeamError::InvalidAxes if minor_deg > major_deg, and BeamError::NotFinite if any value is NaN or infinite.

Examples

use convolve_rs::Beam;

let beam = Beam::new(20.0 / 3600.0, 10.0 / 3600.0, 45.0)?;
assert_eq!(beam.pa_deg, 45.0);

// Minor axis larger than major is rejected.
assert!(Beam::new(10.0 / 3600.0, 20.0 / 3600.0, 0.0).is_err());

pub fn from_arcsec( major_arcsec: f64, minor_arcsec: f64, pa_deg: f64, ) -> Result<Self, BeamError>

Create a beam from FWHM axes in arcseconds and a position angle in degrees East of North.

Examples

use convolve_rs::Beam;

let beam = Beam::from_arcsec(20.0, 10.0, 45.0)?;
assert_eq!(beam.minor_deg, 10.0 / 3600.0);

pub fn zero() -> Self

pub fn major_arcsec(&self) -> f64

pub fn minor_arcsec(&self) -> f64

pub fn is_finite(&self) -> bool

pub fn is_zero(&self) -> bool

pub fn is_circular(&self, rtol: f64) -> bool

pub fn area_sr(&self) -> f64

pub fn deconvolve(&self, other: &Beam) -> Result<Beam, BeamError>

Deconvolve other from self (i.e. self = result ⊛ other).

Subtracts the covariance of other from that of self and reads off the residual ellipse. Fails if the residual is not positive-definite (the source beam is not larger than the PSF). Inputs/outputs in degrees.

Examples

Deconvolution inverts convolution:

use convolve_rs::Beam;

let a = Beam::from_arcsec(10.0, 8.0, 30.0)?;
let b = Beam::from_arcsec(6.0, 5.0, 15.0)?;
let recovered = a.convolve(&b).deconvolve(&a)?;
assert!((recovered.major_arcsec() - b.major_arcsec()).abs() < 1e-6);
assert!((recovered.minor_arcsec() - b.minor_arcsec()).abs() < 1e-6);

// Deconvolving a larger beam from a smaller one fails.
assert!(b.deconvolve(&a).is_err());

pub fn deconvolve_or_zero(&self, other: &Beam) -> Beam

Like deconvolve but returns a zero beam on failure instead of an error.

pub fn convolve(&self, other: &Beam) -> Beam

Convolve self with other: sum the covariance matrices and read off the resulting ellipse.

Examples

Convolving two circular beams adds their axes in quadrature:

use convolve_rs::Beam;

let a = Beam::from_arcsec(3.0, 3.0, 0.0)?;
let b = Beam::from_arcsec(4.0, 4.0, 0.0)?;
let c = a.convolve(&b);
assert!((c.major_arcsec() - 5.0).abs() < 1e-9);

pub fn approx_eq(&self, other: &Beam) -> bool

Approximate equality with a tolerance of ~1e-10 degrees (~0.4 nanoarcsec).

Trait Implementations

impl Clone for Beam

fn clone(&self) -> Beam

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for Beam

impl Debug for Beam

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Beam

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl PartialEq for Beam

fn eq(&self, other: &Self) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.