Add minkowski metric in polar coordinates

[ritzvik]

🐞 Problem
Currently minkowski metric is defined in cartesian coordinates. We need MinkowskiPolar.

🎯 Goal

The metric expression is diag(-1, 1, r ** 2, r ** 2 * sin(theta) ** 2). Include c(speed of light) in a similar fashion to that of given below.

💡 Possible solutions

New addition expected in the same file as given below :

einsteinpy/src/einsteinpy/symbolic/predefined/minkowski.py

Lines 7 to 20 in 08411f1

	def Minkowski(c=constants.c):
	"""
	Minkowski(flat) space-time. Space-time without any curvature or matter.
	Parameters
	----------
	c : ~sympy.core.basic.Basic or int or float
	Any value to assign to speed of light. Defaults to 'c'.
	"""
	coords = symbols("t x y z")
	metric = diag(-1, 1 / (c ** 2), 1 / (c ** 2), 1 / (c ** 2)).tolist()
	return MetricTensor(metric, coords, "ll")

📋 Steps to solve the problem

• Comment below about what you've started working on.
• Add, commit, push your changes
• Submit a pull request and add this in comments - Addresses #<put issue number here>
• Ask for a review in comments section of pull request
• Celebrate your contribution to this project 🎉

[mightomi]

I would love to work on this issue if i can.

[ritzvik]

Good first issues are meant to be a starting point to newcomers. Please try to look for more advanced issues from now on :)

…

On Sun, Mar 22, 2020 at 9:47 PM Swastik Singh ***@***.***> wrote: I would love to work on this issue if i can. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#450 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AF4NHVF6KUDFSSKC73I22WDRIY22FANCNFSM4LRJNVKQ> .

[mightomi]

Okay :)

[gravitas21]

@ritzvik Can I work on this?

[ritzvik]

@ritzvik Can I work on this?

Go ahead 😃