NAME: hemr PURPOSE: (one line) Compute the hemispherical reflectance DESCRIPTION: This function is coded from equation 12.10 on page 365 in Hapke's book, "Theory of Reflectance and Emittance Spectroscopy". CATEGORY: Miscellaneous CALLING SEQUENCE: ans = hemr(w,imu,holes,p,b0,theta) INPUTS: w - Single scattering albedo. imu - Cosine of the incidence angle. holes - Compaction parameter value (1986 formalism). p - Parameters of the single particle phase function (default "function" is a constant of value p, this is not very useful for this routine and is not recommended). There are two legal input forms for p: 1. an array of dimensionality Pparms 2. an array of dimensionality (n_elements(w),Pparms) b0 - Backscatter value. theta - Surface roughness value. (radians) OPTIONAL INPUT PARAMETERS: None. KEYWORD PARAMETERS: nmu - number of points between 0 and 1 at which to evaluate mu = cos(e). Default 6. nphi - number of points between 0 and pi at which to evaluate phi Default 6. H93 - Flag passed to bidr2, if set, uses the 1993 version of Hapke's approximation to the Chandresekar H function. The 1993 version is more accurate but considerably slower to compute. Pfn - Flag passed to bidr2. REQUIRED. Specify function to use for P(g) instead of the default constant. The function must be a procedure taking arguments g,a,F,/radians g phase angle in radians (with keyword /radians set) a an array of Pparms parameters F phase function evaluated at phase angles g Use "fn_hg3.pro" as a model. Pparms- Flag passed to bidr2. Specify number of parameters to be passed to P(g). Really only needed if the number of parameters isn't one. pedantic - Flag pased to bidr, if set, returns NaN for w > 1. OUTPUTS: Return value is the hemispherical reflectance. COMMON BLOCKS: None. SIDE EFFECTS: None. RESTRICTIONS: Any input may be a vector. If more than one is a vector then the lengths must match. The return will have the same dimensions as the input. PROCEDURE: MODIFICATION HISTORY: Written by Leslie Young, SwRI, 2010/12/28, cloned from bidr2 where similar