Read a size distribution from a data file.

Parameters

[in,out]	file	Spec file to read size distribution from.
[in,out]	sample_radius	Sample radius values (m).
[in,out]	sample_num_conc	Sample number concentrations (m^{-3}).

A size distribution file must consist of two lines:

the first line must begin with diam and be followed by space-separated real scalars, giving the diameters $D_1,\ldots,D_{N+1}$ of bin edges (m) — these must be in increasing order, so $D_i < D_{i+1}$
the second line must begin with num_conc and be followed by space-separated real scalars, giving the number concenrations $C_1,\ldots,C_N$ in each bin (#/m^3) — is the total number concentrations of particles with diameters in $[D_i, D_{i+1}]$

The resulting size distribution is taken to be piecewise constant in log-diameter coordinates.

Example: a size distribution could be:

 diam 1e-7 1e-6 1e-5  # bin edge diameters (m)
 num_conc 1e9 1e8     # bin number concentrations (m^{-3})

This distribution has 1e9 particles per cubic meter with diameters between 0.1 micron and 1 micron, and 1e8 particles per cubic meter with diameters between 1 micron and 10 micron.