.. _quickstart:

Quickstart
============
If you're in a hurry to model some awesome transits, you're on the right page.  Here's an example of basic ``robin`` usage to calculate a model light curve with quadratic limb darkening.  (For more detailed examples, check out the :ref:`tutorial`.)

First, we import ``robin`` and a few of the usual packages:

::

	import robin
	import numpy as np
	import matplotlib.pyplot as plt

Next we create a ``TransitParams`` object to store the physical parameters describing the transit:

::

	params = robin.TransitParams()
	params.t0 = 0. 			     #time of inferior conjunction 
	params.per = 1.			     #orbital period	
	params.rp = 0.1			     #planet radius (in units of stellar radii)
	params.a = 15.			     #semi-major axis (in units of stellar radii)
	params.inc = 87.		     #orbital inclination (in degrees)	
	params.ecc = 0.			     #eccentricity	
	params.w = 90.		   	     #longitude of periastron (in degrees)
	params.u = [0.1, 0.3]  	             #limb darkening coefficients [u1, u2]
	params.limb_dark = "quadratic"       #limb darkening model

Note that for circular orbits, ``robin`` uses the convention ``params.w = 90``.  The units for ``params.t0`` and ``params.per`` can be anything as long as they are consistent.

We also need to specify the times at which we wish to calculate the model:

::

	t = np.linspace(-0.05, 0.05, 100)    

Using these parameters, we initialize the model and calculate a model light curve: 

::

	m = robin.TransitModel(params, t)    #initializes model
	flux = m.light_curve(params)	      #calculates light curve


Voilà!  Here's a figure showing the light curves:

::

	plt.plot(t, flux)
	plt.xlabel("Time from central transit")
	plt.ylabel("Relative flux")
	plt.show()


.. image:: lc.png

This code is available in full at https://github.com/bmorris3/robin/tree/master/docs/quickstart.py.