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measures.doppler - Function

1.4.1 define a doppler measure


Description

doppler defines a doppler measure from the CLI. It has to specify a reference code, doppler quantity value (see introduction for the action on a scalar quantity with either a vector or scalar value),

and optionally it can specify an offset, which in itself has to be a doppler. Allowable reference codes are: RADIO Z RATIO BETA GAMMA OPTICAL TRUE RELATIVISTIC.
Note that additional ones may become available. Check in CASA with:

print "\t----\t doppler Ex 1 \t----"  
print me.listcodes(me.doppler())  
#{’normal’: [’RADIO’, ’Z’, ’RATIO’, ’BETA’, ’GAMMA’, ’OPTICAL’,  
# ’TRUE’, ’RELATIVISTIC’], ’extra’: []}

The doppler quantity values should be either non-dimensioned to specify a ratio of the light velocity, or in velocity.

Arguments





Inputs

rf

reference code

allowed:

string

Default:

RADIO

v0

doppler ratio/velocity

allowed:

any

Default:

variant

off

optional offset doppler measure

allowed:

record

Default:

Returns
record

Example

 
Examples both give same doppler:  
 
print "\t----\t doppler Ex 2 \t----"  
print me.doppler(’radio’,’0.4’)  
#{’m0’: {’value’: 119916983.2, ’unit’: ’m/s’},  
# ’refer’: ’RADIO’,  
# ’type’: ’doppler’}  
print me.doppler(’radio’,qa.mul(qa.quantity(’0.4’),qa.constants(’c’)))  
#{’m0’: {’value’: 119916983.2, ’unit’: ’m/s’},  
# ’refer’: ’RADIO’,  
# ’type’: ’doppler’}  
 

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