Read the specification for a radius bin_grid from a spec file.

Parameters

[in,out]	file	Spec file.
[in,out]	bin_grid	Radius bin grid.

The diameter bin grid is logarithmic, consisting of $n_{\rm bin}$ bins with centers ( $i = 1,\ldots,n_{\rm bin}$ ) and edges ( $i = 1,\ldots,(n_{\rm bin} + 1)$ ) such that $e_{i+1}/e_i$ is a constant and $c_i/e_i = \sqrt{e_{i+1}/e_i}$ . That is, $\ln(e_i)$ are uniformly spaced and $\ln(c_i)$ are the arithmetic centers.

The diameter axis bin grid is specified by the parameters:

n_bin (integer): The number of bins $n_{\rm bin}$ .
d_min (real, unit m): The left edge of the left-most bin, .
d_max (real, unit m): The right edge of the right-most bin, $e_{n_{\rm bin} + 1}$ .