Positive Values of Harmonic Polynomials
Trudy Matematicheskogo Instituta imeni V.A. Steklova, Function spaces, approximations, and differential equations, Tome 243 (2003), pp. 46-52
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It is proved that, among all second-order spherical harmonics $Y_2$, the quantity $\mathrm {meas}\{x\in S^2\colon Y_2(x)\ge 0\}$ attains its minimal value at a zonal polynomial. For harmonics of higher even orders, the situation is different. Several examples are considered.
@article{TM_2003_243_a4,
author = {N. N. Andreev and V. A. Yudin},
title = {Positive {Values} of {Harmonic} {Polynomials}},
journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
pages = {46--52},
year = {2003},
volume = {243},
language = {ru},
url = {http://geodesic.mathdoc.fr/item/TM_2003_243_a4/}
}
N. N. Andreev; V. A. Yudin. Positive Values of Harmonic Polynomials. Trudy Matematicheskogo Instituta imeni V.A. Steklova, Function spaces, approximations, and differential equations, Tome 243 (2003), pp. 46-52. http://geodesic.mathdoc.fr/item/TM_2003_243_a4/
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