Thread: index on PolesZerosType, FIRType, not on CoefficientsType

Started: 2013-04-11 22:08:09
Last activity: 2013-04-11 22:08:09
Topics: Web Services
Philip Crotwell
2013-04-11 22:08:09
So PoleZeroType (used in PolesZerosType) has a "number" attribute.

NumeratorCoefficient in FIRType has a "i" attribute, presumably for the
same indexing purpose.

CoefficientType, which is very similar to FIRType in actual usage (ie a FIR
is a like a Coefficient with no denominators) has Numerator as a FloatType,
which does not have an indexing attribute .

ResponseListType which has ResponseListElementTypes, also has no indexing
attribute.

PolynomialType has Coefficient as FloatNoUnitType but does have a "number"
indexing attribute.

Other things besides subtypes of ResponseStageType are indexed as well,
like the actual ResponseStageType, indexed with a "number" attribute and
Comment indexed with a "id" attribute.

In actual usage from the iris fdsnws/station, it appears to me that only
poles and zeros actually make use of the indexing attribute. Not clear why
order would be more important for poles/zeros as opposed to the other
types. In fact I think order does not matter mathematically for poles and
zeros (multiplication is commutative), but it does matter very much for
coefficients of a polynomial!

Is there any rhyme or reason as to when indexing attributes are used? If
indexing of poles, zeros, coefficients, numerators and denominators seem to
me like they should all be the same, either available for all or not
available for all. And if they are there, they should use the same
attribute name as the index.

Another question is why FIRType would use a basic double, while
CoefficientType makes use of FloatType when they are basically the same
type of information.

thanks
Philip

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