Merged with other entry at http://www.mathworks.com/matlabcentral/fileexchange/28135-standard-atmosphere-functions
This entry will not be kept up to date.

H = DENSITYALT(RHO,Param1,Val1,Param2,Val2,...) returns altitude, H, as a function of air density, RHO.
The input RHO can be followed by parameter/value pairs for further control:
inputUnits - String for units of input RHO, either kg/m³ or slug/ft³.
outputUnits - String for units of output H, either meters or feet.
atmosphereFunc - String determining atmosphere function to be used ( stdatmo | atmosisa | atmoscoesa | atmosnonstd ).
atmosphereArgs - Cell array of additional arguments to pass to atmosphereFunction after the density input (e.g. for non-standard atmospheres).
method - Method used for either searching for (with fzero or bisection) or interpolating a solution (the equations that define the standard atmosphere cannot be inverted in terms of density).
options - Options used for fzero or bisection methods.
and others.