Class: VORuby::CoordinateSystems::Equatorial::Declination

Inherits:
Object
  • Object
show all
Defined in:
lib/voruby/spacetime/spacetime.rb

Constant Summary collapse

MIN_ALLOWED_VALUE = 
-90.0
MAX_ALLOWED_VALUE = 
90.0

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(dec) ⇒ Declination

Create a Declination object from a decimal number.



395
396
397
 
# File 'lib/voruby/spacetime/spacetime.rb', line 395

def initialize(dec)
  self.value = dec
end

Instance Attribute Details

#value ⇒ Object

Returns the value of attribute value.



389
390
391
 
# File 'lib/voruby/spacetime/spacetime.rb', line 389

def value
  @value
end

Class Method Details

.from_sexigesimal(dec) ⇒ Object

Create a Declination object from a string in sexigesimal format. Numerical values may be separated by a space or colon (but not both).

Raises:



423
424
425
426
427
428
429
430
431
432
433
 
# File 'lib/voruby/spacetime/spacetime.rb', line 423

def self.from_sexigesimal(dec)
  raise Exception::InvalidSexigesimalFormat.new(dec) if !Equatorial::looks_like_sexigesimal?(dec)

  degree, arcmin, arcsec = dec.split(/:|\s+/)
  degree_f = degree.to_f()
  arcmin_f = (arcmin.to_f() / 60.0)
  arcsec_f = (arcsec.to_f() / (60.0 * 60.0))

  return Declination.new(degree_f - arcmin_f - arcsec_f) if degree_f < 0
  return Declination.new(degree_f + arcmin_f + arcsec_f)
end

.in_range?(dec) ⇒ Boolean

Is the supplied number in the correct range for a declination (i.e between -90 and 90 degrees)?

Returns:

  • (Boolean) 


417
418
419
 
# File 'lib/voruby/spacetime/spacetime.rb', line 417

def self.in_range?(dec)
  (MIN_ALLOWED_VALUE..MAX_ALLOWED_VALUE) === dec
end

Instance Method Details

#+(degrees) ⇒ Object

Returns a declination object projected forward the specified number of degrees. Note that if the new object will have a value greater than 90 degrees, the declination will be assumed to be exactly 90 degrees, and similarly for -90 degrees.



455
456
457
458
459
460
461
 
# File 'lib/voruby/spacetime/spacetime.rb', line 455

def +(degrees)
  new_degrees = self.value + degrees
  new_degrees = MAX_ALLOWED_VALUE if new_degrees > MAX_ALLOWED_VALUE
  new_degrees = MIN_ALLOWED_VALUE if new_degrees < MIN_ALLOWED_VALUE

  Declination.new(new_degrees)
end

#-(degrees) ⇒ Object

Returns a declination object projected backwards the specified number of degrees. Note that if the new object will have a value greater less than -90 degrees, the declination will be assumed to be exactly -90 degrees.



473
474
475
476
477
478
 
# File 'lib/voruby/spacetime/spacetime.rb', line 473

def -(degrees)
  new_degrees = self.value - degrees
  new_degrees = MIN_ALLOWED_VALUE if new_degrees < MIN_ALLOWED_VALUE

  Declination.new(new_degrees)
end

#<=>(dec) ⇒ Object 



486
487
488
 
# File 'lib/voruby/spacetime/spacetime.rb', line 486

def <=>(dec)
  self.value <=> dec.value
end

#==(dec) ⇒ Object 



490
491
492
 
# File 'lib/voruby/spacetime/spacetime.rb', line 490

def ==(dec)
  self.value == dec.value
end

#decrement(degrees) ⇒ Object

Subtract the specified number of degrees from the dec.



481
482
483
484
 
# File 'lib/voruby/spacetime/spacetime.rb', line 481

def decrement(degrees)
  new_degrees = self - degrees
  self.value = new_degrees.value
end

#increment(degrees) ⇒ Object

Add the specified number of degrees to the dec.



464
465
466
467
 
# File 'lib/voruby/spacetime/spacetime.rb', line 464

def increment(degrees)
  new_degrees = self + degrees
  self.value = new_degrees.value
end

#to_s ⇒ Object 



494
495
496
 
# File 'lib/voruby/spacetime/spacetime.rb', line 494

def to_s
  "#{self.to_sexigesimal}"
end

#to_sexigesimal(sep = ':') ⇒ Object

Return the value of the dec as a string in sexigesimal format.



436
437
438
439
440
441
442
443
444
445
446
447
448
449
 
# File 'lib/voruby/spacetime/spacetime.rb', line 436

def to_sexigesimal(sep=':')
  degrees = self.value  
  decsign = '+'
  if degrees < 0
    decsign = '-'
    degrees = -degrees
  end
  decd = degrees.to_i()
  decm = ((degrees - decd) * 60.0).to_i()
  decs = degrees - decd - (decm / 60.0)
  decs = decs * 60.0 * 60.0

  return sprintf("%s%02u#{sep}%02u#{sep}%0.2f", decsign, decd, decm, decs)
end