Function to set by reference the "time.unit" attribute of an
existing source_spct object, and function to query its value.
setBSWFUsed(x, bswf.used = c("none", "unknown"))getBSWFUsed(x)
x or the character value stored in x.
a source_spct object.
a character string, either "none" or the name of a
BSWF.
Effective spectral irradiance, describes an estimate of the strength of the radiation towards eliciting a given response, frequently, but not only a biological response. The biological spectral weighting function, BSWF, used, can be for example that of the human eye, or an action spectrum, such as the erythema, or reddening of the human skin, action spectrum.
$$I_{BE}(\lambda) = I(\lambda) \times f_{BE}(\lambda)$$
where, \(I_{BE}(\lambda)\) is the biologically effective spectral irradiance, \(I(\lambda)\) is the spectral irradiance and \(f_{BE}(\lambda)\) is one of many possible BSWF.
When the values stored in a source_spct object have been multiplied
by those from a curve describing a certain response or effect, the
attribute "time.unit" is set accordingly to track the transformation
applied to the data. When a spectral response data have been directly measured,
they should be stored in an object of class response_spct as they
are expressed in actual response units, not
of class source_spct expressed in irradiance units, even if weighted.
However, when like in the case of spectral
illuminance, the aim is technical measure of a light source,
class source_spct should be used and the BSWF set in the metadata.
This attribute is normally set by the function or operator used to apply
the BSWF to spectral irradiance data, or set when the source_spct object
is created.