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scottprahl / mie

Mie code to calculate light scattering by perfect spheres.
BSD 3-Clause "New" or "Revised" License
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installation still gives ctangle issue #2

Closed PiyushX23 closed 4 years ago

PiyushX23 commented 4 years ago

Hi...

sorry I was out for last week, but I am still facing the same issue regarding ctangle, while installing mie. Following is an error, I am facing.

ctangle -bph test_mie make[1]: ctangle: Command not found

Additionally, can you help me to suggest, how one can calculate backscattering efficiency using Wiscombe code? because I think Wiscombe Fortran code does not directly provide backscattering efficiency.

Thank you

scottprahl commented 4 years ago

yep, you're right. I missed those. I just uploaded those to github. Please do a git pull and try to rebuild.

PiyushX23 commented 4 years ago

Hi... thank you for your supports. The issue got resolved and I installed it successfully. can you suggest me, how one can calculate backscattering efficiency using Wiscombe code? because I think Wiscombe Fortran code does not directly provide backscattering efficiency.

scottprahl commented 4 years ago

The backscattering efficiency is calculated for you.

void Mie(double x, struct c_complex m, double *mu, long nangles, struct c_complex *s1, 
           struct c_complex *s2, double *qext, double *qsca, double *qback, double *g)

The details of the calculation are on page 44 of the documentation in doc/mie_doc.pdf and follow that given in the usual texts Bohren & Huffman or van de Hulst

PiyushX23 commented 4 years ago

Thank you, Scott, for your kind help.

I have a query regarding your python version of Mie code.

I was trying to compare the results from original BHMIE Fortran code and miepython (a python version of your code). I found that both provide similar results of extinction and scattering efficiencies but backscatter efficiency is different. MiePython (python version provides) 10 order of higher value of backscatter than BHMIE code.

Here is my python script for MiePython

import miepython as mp m=1.77-0.63j radius=150nm wavelength=375nm x=2.512 qext,qsca,qback=mp.mie(m,x)

outcomes: qext=2.858594660377669 qsca=1.314966237440868 QBACK=0.20212578330774

The input and outcome of BHMIE code is attached here as a text file

Best Regards Piyushkumar Patel

NASA Postdoctoral Fellow Aerosols & Clouds (329J) Jet Propulsion Laboratory, Mail Stop 183-715,

4800 Oak Grove Drive, Pasadena, California 91109, USA

Tel: +1-818-354-3234 alternate email: piyushkumar.n.patel@jpl.nasa.gov piyushpatel@prl.res.in

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On Mon, Oct 14, 2019 at 7:27 PM Scott Prahl notifications@github.com wrote:

The backscattering efficiency is calculated for you.

void Mie(double x, struct c_complex m, double mu, long nangles, struct c_complex s1, struct c_complex s2, double qext, double qsca, double qback, double *g)

The details of the calculation are on page 44 of the documentation in doc/mie_doc.pdf and follow that given in the usual texts Bohren & Huffman or van de Hulst

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scottprahl commented 4 years ago

Ack. I replied by email instead of on issue tracker.

The problem is the definition of backscattering efficiency. The one that I use (Wiscombe's) which evidently differs from that of Bohren & Huffman by a factor of 4pi.

The is explained in https://github.com/scottprahl/miepython/blob/master/doc/02_efficiencies.ipynb