sphere.cnb

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					"source" : "\\section*{Two-sphere}\n\nThis notebook computes the curvature of a 2-sphere by computing connection coefficients and the\nRiemann tensor components."
				}
			],
			"hidden" : true,
			"source" : "\\section*{Two-sphere}\n\nThis notebook computes the curvature of a 2-sphere by computing connection coefficients and the\nRiemann tensor components."
		},
		{
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			"cell_type" : "input",
			"cells" : 
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					"source" : "\\begin{dmath*}{}\\text{Attached property Coordinate to~}\\left[\\theta,~\\discretionary{}{}{} \\varphi\\right].\\end{dmath*}"
				},
				{
					"cell_origin" : "server",
					"cell_type" : "latex_view",
					"source" : "\\begin{dmath*}{}\\text{Attached property Indices(position=fixed) to~}\\left[\\alpha,~\\discretionary{}{}{} \\beta,~\\discretionary{}{}{} \\gamma,~\\discretionary{}{}{} \\delta,~\\discretionary{}{}{} \\rho,~\\discretionary{}{}{} \\sigma,~\\discretionary{}{}{} \\mu,~\\discretionary{}{}{} \\nu,~\\discretionary{}{}{} \\lambda\\right].\\end{dmath*}"
				},
				{
					"cell_origin" : "server",
					"cell_type" : "latex_view",
					"source" : "\\begin{dmath*}{}\\text{Attached property PartialDerivative to~}\\partial{\\#}.\\end{dmath*}"
				}
			],
			"source" : "{\\theta, \\varphi}::Coordinate;\n{\\alpha, \\beta, \\gamma, \\delta, \\rho, \\sigma, \\mu, \\nu, \\lambda}::Indices(values={\\varphi, \\theta}, position=fixed);\n\\partial{#}::PartialDerivative;\ng_{\\alpha\\beta}::Metric.\ng^{\\alpha\\beta}::InverseMetric."
		},
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			"cells" : 
			[
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					[
						{
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							"source" : "{g_{\\theta \\theta} = (r)**2, g_{\\varphi \\varphi} = (r)**2 (\\sin(\\theta))**2, g^{\\varphi \\varphi} = ((r)**2 (\\sin(\\theta))**2)**-1, g^{\\theta \\theta} = (r)**-2}"
						}
					],
					"source" : "\\begin{dmath*}{}\\left[g_{\\theta \\theta} = {r}^{2},~\\discretionary{}{}{} g_{\\varphi \\varphi} = {r}^{2} {\\left(\\sin{\\theta}\\right)}^{2},~\\discretionary{}{}{} g^{\\varphi \\varphi} = {\\left({r}^{2} {\\left(\\sin{\\theta}\\right)}^{2}\\right)}^{-1},~\\discretionary{}{}{} g^{\\theta \\theta} = {r}^{-2}\\right]\\end{dmath*}"
				}
			],
			"source" : "sphe:={ g_{\\theta\\theta} = r**2,\n         g_{\\varphi\\varphi} = r**2 \\sin(\\theta)**2 }.\ncomplete(sphe, $g^{\\alpha\\beta}$);"
		},
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			[
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					"source" : "The Christoffel symbols are given in terms of the metric by the following expression."
				}
			],
			"hidden" : true,
			"source" : "The Christoffel symbols are given in terms of the metric by the following expression."
		},
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			"cells" : 
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							"source" : "\\Gamma^{\\alpha}_{\\mu \\nu} =  1/2 g^{\\alpha \\beta} (\\partial_{\\nu}(g_{\\beta \\mu}) + \\partial_{\\mu}(g_{\\beta \\nu})-\\partial_{\\beta}(g_{\\mu \\nu}))"
						}
					],
					"source" : "\\begin{dmath*}{}\\Gamma^{\\alpha}\\,_{\\mu \\nu} = \\frac{1}{2}g^{\\alpha \\beta} \\left(\\partial_{\\nu}{g_{\\beta \\mu}}+\\partial_{\\mu}{g_{\\beta \\nu}}-\\partial_{\\beta}{g_{\\mu \\nu}}\\right)\\end{dmath*}"
				}
			],
			"source" : "ch:= \\Gamma^{\\alpha}_{\\mu\\nu} = 1/2 g^{\\alpha\\beta} ( \\partial_{\\nu}{g_{\\beta\\mu}}\n                                                      +\\partial_{\\mu}{g_{\\beta\\nu}}\n                                                      -\\partial_{\\beta}{g_{\\mu\\nu}} );"
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					"source" : "We evaluate the components using \\verb|evaluate| and then massage them a bit further using sympy."
				}
			],
			"hidden" : true,
			"source" : "We evaluate the components using \\verb|evaluate| and then massage them a bit further using sympy."
		},
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			"cell_origin" : "client",
			"cell_type" : "input",
			"cells" : 
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							"source" : "\\Gamma^{\\alpha}_{\\mu \\nu} = \\components_{\\mu \\nu}^{\\alpha}({{\\varphi, \\theta, \\varphi} = (\\tan(\\theta))**-1, {\\theta, \\varphi, \\varphi} = (\\tan(\\theta))**-1, {\\varphi, \\varphi, \\theta} = -\\sin(\\theta) \\cos(\\theta)})"
						}
					],
					"source" : "\\begin{dmath*}{}\\Gamma^{\\alpha}\\,_{\\mu \\nu} = \\square{}_{\\mu}{}_{\\nu}{}^{\\alpha}\\left\\{\\begin{aligned}\\square{}_{\\varphi}{}_{\\theta}{}^{\\varphi}= & {\\left(\\tan{\\theta}\\right)}^{-1}\\\\[-.5ex]\n\\square{}_{\\theta}{}_{\\varphi}{}^{\\varphi}= & {\\left(\\tan{\\theta}\\right)}^{-1}\\\\[-.5ex]\n\\square{}_{\\varphi}{}_{\\varphi}{}^{\\theta}= & -\\sin{\\theta} \\cos{\\theta}\\\\[-.5ex]\n\\end{aligned}\\right.\n\\end{dmath*}"
				}
			],
			"source" : "evaluate(ch, sphe, rhsonly=True)\nmap_sympy(ch, \"expand_trig\");"
		},
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			"cell_origin" : "client",
			"cell_type" : "latex",
			"cells" : 
			[
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					"cell_origin" : "client",
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					"source" : "The Riemann tensor is given in terms of the Christoffel symbols by the expression below. "
				}
			],
			"hidden" : true,
			"source" : "The Riemann tensor is given in terms of the Christoffel symbols by the expression below. "
		},
		{
			"cell_origin" : "client",
			"cell_type" : "input",
			"cells" : 
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						{
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							"source" : "R^{\\rho}_{\\sigma \\mu \\nu} = \\partial_{\\mu}(\\Gamma^{\\rho}_{\\sigma \\nu})-\\partial_{\\nu}(\\Gamma^{\\rho}_{\\sigma \\mu}) + \\Gamma^{\\rho}_{\\beta \\mu} \\Gamma^{\\beta}_{\\sigma \\nu}-\\Gamma^{\\rho}_{\\beta \\nu} \\Gamma^{\\beta}_{\\sigma \\mu}"
						}
					],
					"source" : "\\begin{dmath*}{}R^{\\rho}\\,_{\\sigma \\mu \\nu} = \\partial_{\\mu}{\\Gamma^{\\rho}\\,_{\\sigma \\nu}}-\\partial_{\\nu}{\\Gamma^{\\rho}\\,_{\\sigma \\mu}}+\\Gamma^{\\rho}\\,_{\\beta \\mu} \\Gamma^{\\beta}\\,_{\\sigma \\nu}-\\Gamma^{\\rho}\\,_{\\beta \\nu} \\Gamma^{\\beta}\\,_{\\sigma \\mu}\\end{dmath*}"
				},
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					"cell_origin" : "server",
					"cell_type" : "latex_view",
					"cells" : 
					[
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							"source" : "R^{\\rho}_{\\sigma \\mu \\nu} = \\components_{\\sigma \\nu}^{\\rho}_{\\mu}({{\\varphi, \\varphi, \\theta, \\theta} = (\\sin(\\theta))**2, {\\theta, \\varphi, \\varphi, \\theta} = -1, {\\varphi, \\theta, \\theta, \\varphi} = -(\\sin(\\theta))**2, {\\theta, \\theta, \\varphi, \\varphi} = 1})"
						}
					],
					"source" : "\\begin{dmath*}{}R^{\\rho}\\,_{\\sigma \\mu \\nu} = \\square{}_{\\sigma}{}_{\\nu}{}^{\\rho}{}_{\\mu}\\left\\{\\begin{aligned}\\square{}_{\\varphi}{}_{\\varphi}{}^{\\theta}{}_{\\theta}= & {\\left(\\sin{\\theta}\\right)}^{2}\\\\[-.5ex]\n\\square{}_{\\theta}{}_{\\varphi}{}^{\\varphi}{}_{\\theta}= & -1\\\\[-.5ex]\n\\square{}_{\\varphi}{}_{\\theta}{}^{\\theta}{}_{\\varphi}= & -{\\left(\\sin{\\theta}\\right)}^{2}\\\\[-.5ex]\n\\square{}_{\\theta}{}_{\\theta}{}^{\\varphi}{}_{\\varphi}= & 1\\\\[-.5ex]\n\\end{aligned}\\right.\n\\end{dmath*}"
				}
			],
			"source" : "rm:= R^{\\rho}_{\\sigma\\mu\\nu} = +\\partial_{\\mu}{\\Gamma^{\\rho}_{\\sigma\\nu}}\n                           -\\partial_{\\nu}{\\Gamma^{\\rho}_{\\sigma\\mu}}\n                           +\\Gamma^{\\rho}_{\\beta\\mu} \\Gamma^{\\beta}_{\\sigma\\nu}\n                           -\\Gamma^{\\rho}_{\\beta\\nu} \\Gamma^{\\beta}_{\\sigma\\mu};\n\nsubstitute(rm, ch)\nevaluate(rm, sphe, rhsonly=True);"
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			"cell_type" : "latex",
			"cells" : 
			[
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					"source" : "These are not in the simplest form possible yet, but this is a \\verb|sympy| simplification issue; for the time being\nwe will continue and compute the Ricci tensor and scalar."
				}
			],
			"hidden" : true,
			"source" : "These are not in the simplest form possible yet, but this is a \\verb|sympy| simplification issue; for the time being\nwe will continue and compute the Ricci tensor and scalar."
		},
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			"cell_origin" : "client",
			"cell_type" : "input",
			"cells" : 
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					[
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							"source" : "R_{\\sigma \\nu} = R^{\\rho}_{\\sigma \\rho \\nu}"
						}
					],
					"source" : "\\begin{dmath*}{}R_{\\sigma \\nu} = R^{\\rho}\\,_{\\sigma \\rho \\nu}\\end{dmath*}"
				},
				{
					"cell_origin" : "server",
					"cell_type" : "latex_view",
					"cells" : 
					[
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							"source" : "R_{\\sigma \\nu} = \\components_{\\sigma \\nu}({{\\varphi, \\varphi} = (\\sin(\\theta))**2, {\\theta, \\theta} = 1})"
						}
					],
					"source" : "\\begin{dmath*}{}R_{\\sigma \\nu} = \\square{}_{\\sigma}{}_{\\nu}\\left\\{\\begin{aligned}\\square{}_{\\varphi}{}_{\\varphi}= & {\\left(\\sin{\\theta}\\right)}^{2}\\\\[-.5ex]\n\\square{}_{\\theta}{}_{\\theta}= & 1\\\\[-.5ex]\n\\end{aligned}\\right.\n\\end{dmath*}"
				}
			],
			"source" : "ricci:= R_{\\sigma\\nu} = R^{\\rho}_{\\sigma\\rho\\nu};\nsubstitute(ricci, rm)\nevaluate(ricci, sphe, rhsonly=True);"
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					[
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							"source" : "R = R_{\\sigma \\nu} g^{\\sigma \\nu}"
						}
					],
					"source" : "\\begin{dmath*}{}R = R_{\\sigma \\nu} g^{\\sigma \\nu}\\end{dmath*}"
				},
				{
					"cell_origin" : "server",
					"cell_type" : "latex_view",
					"cells" : 
					[
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							"source" : "R = 2(r)**-2"
						}
					],
					"source" : "\\begin{dmath*}{}R = 2{r}^{-2}\\end{dmath*}"
				}
			],
			"source" : "R:= R = R_{\\sigma\\nu} g^{\\sigma\\nu};\nsubstitute(R, ricci)\nevaluate(R, sphe, rhsonly=True);"
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			"cells" : 
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					"source" : "The main time computing this is spent in the rather inefficient \\verb|sympy| bridge. You can see timing information\nby querying the \\verb|server| object for the \\verb|totals| list."
				}
			],
			"hidden" : true,
			"source" : "The main time computing this is spent in the rather inefficient \\verb|sympy| bridge. You can see timing information\nby querying the \\verb|server| object for the \\verb|totals| list."
		},
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			"cell_origin" : "client",
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					"source" : "{}$\\big[$\\verb|cadabra::collect_terms: 21 calls, 0 steps, 0 ms|,\\discretionary{}{}{} \\verb|cadabra::complete: 1 calls, 0 steps, 268 ms|,\\discretionary{}{}{} \\verb|cadabra::evaluate: 4 calls, 0 steps, 2212 ms|,\\discretionary{}{}{} \\verb|cadabra::map_sympy: 1 calls, 0 steps, 20 ms|,\\discretionary{}{}{} \\verb|cadabra::simplify: 49 calls, 0 steps, 2209 ms|,\\discretionary{}{}{} \\verb|cadabra::substitute: 3 calls, 0 steps, 5 ms|,\\discretionary{}{}{} \\verb|scalar_backend: 49 calls, 0 steps, 2209 ms|,\\discretionary{}{}{} \\verb|sympy: 49 calls, 0 steps, 2209 ms|$\\big]$"
				}
			],
			"source" : "server.totals();"
		},
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			"cell_origin" : "client",
			"cell_type" : "input",
			"source" : ""
		}
	],
	"description" : "Cadabra JSON notebook format",
	"version" : 1
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