Method to compute the "parallel" standard deviation of values across members of a collection of spectra or of a spectral object containing multiple spectra in long form.
s_sd(x, na.rm, ...)# S3 method for default
s_sd(x, na.rm = FALSE, ...)
# S3 method for generic_spct
s_sd(x, na.rm = FALSE, ...)
# S3 method for filter_mspct
s_sd(x, na.rm = FALSE, ...)
# S3 method for source_mspct
s_sd(x, na.rm = FALSE, ...)
# S3 method for response_mspct
s_sd(x, na.rm = FALSE, ...)
# S3 method for reflector_mspct
s_sd(x, na.rm = FALSE, ...)
# S3 method for calibration_mspct
s_sd(x, na.rm = FALSE, ...)
# S3 method for cps_mspct
s_sd(x, na.rm = FALSE, ...)
# S3 method for raw_mspct
s_sd(x, na.rm = FALSE, ...)
If x is a collection spectral of objects, such as a
"filter_mspct" object, the returned object is of same class as the
  members of the collection, such as "filter_spct", containing the
  summary spectrum, with variables with names tagged for summaries other
  than mean or median.
An R object. Currently this package defines methods for collections of spectral objects.
logical. A value indicating whether NA values should be stripped before the computation proceeds.
Further arguments passed to or from other methods.
s_sd(default):
s_sd(generic_spct):
s_sd(filter_mspct):
s_sd(source_mspct):
s_sd(response_mspct):
s_sd(reflector_mspct):
s_sd(calibration_mspct):
s_sd(cps_mspct):
s_sd(raw_mspct):
Method specializations compute the standard deviation at each
  wavelength across a group of spectra stored in an object of one of the
  classes defined in package 'photobiology'. Omission of NAs is done
  separately at each wavelength. Interpolation is not applied, so all spectra
  in x must share the same set of wavelengths. An error is triggered
  if this condition is nor fulfilled.