This IDL facility provides a means to bin an angular power spectrum into arbitrary bins.

Location in HEALPix directory tree: src/idl/misc/bin_llcl.pro

FORMAT

IDL> BIN_LLCL, Llcl_in, Bin, L_out, Llcl_out, [Dllcl, DELTAL=, /FLATTEN, /HELP, /UNIFORM]

QUALIFIERS

Llcl_in: 1D vector: input power spectrum (given for each l starting at 0).
Bin: input: binning in l to be applied,
-either a scalar interpreted as the step size of a regular binning, the first bins are then {0, bin - 1},{bin, 2bin-1}, $\ldots$
-or a 1D vector, interpreted as the lower bound of each bin, ie the first bins are {bin[0],bin[1]-1}, {bin[1], bin[2]-1}, $\ldots$
L_out: contains on output the center of each bin l_b.
Llcl_out: contains on output the binned power spectrum C(b), ie the (weighted) average of the input C(l) over each bin.
Dllcl: optional, contains on output a rough estimate of the rms of the binned C(l) for a full sky observation $C(b) \sqrt{ 2 / ((2l_b+1) \Delta l_b)}$
DELTAL=: optional, contains on output the size of each bin $\Delta l(b)$

KEYWORDS

/FLATTEN: if set, the C(l) is internally multiplied by $l(l+1)/2\pi$ before being binned.
By default, the input Llcl_in is binned as is.
/HELP: if set, an extended help is printed and the code exits.
/UNIFORM: if set, the C(l) in each bin is given the same weight.
By default a weight $\propto 2l+1$ is used (inverse cosmic variance weighting). Note that this weighting affects Llcl_out but not L_out.

DESCRIPTION

bin_llcl bins the input power spectrum (as is, or after flattening by a $\l (\l +1)/2\pi$ factor) according to an arbitrary binning scheme defined by the user. Different weighting scheme (uniform or inverse variance) can be applied inside the bins.