Planck's law In 1880, André-Prosper-Paul Crova published a diagram of the three-dimensional appearance of the graph of the strength of thermal radiation as a function of wavelength and temperature. He determined the spectral variable by use of prisms. He analyzed the surface through what he called "isothermal" curves, sections for a single temperature, with a spectral variable on the abscissa and a power variable on the ordinate. He put smooth curves through his experimental data points. They had one peak at a spectral value characteristic for the temperature, and fell either side of it towards the horizontal axis. Such spectral sections are
Minimum rank of a graph Minimum rank of a graph In mathematics, the minimum rank is a graph parameter formula_1 for any graph "G". It was motivated by the Colin de Verdière's invariant. The adjacency matrix of a given undirected graph is a symmetric matrix whose rows and columns both correspond to the vertices of the graph. Its coefficients are all 0 or 1, and the coefficient in row "i" and column "j" is nonzero whenever vertex "i" is adjacent to vertex "j" in the graph. More generally, one can define a "generalized adjacency matrix" to be any matrix of real numbers with the same