"Even the +, −, =, and x signs we take for granted only came into widespread use in the 17th century. Which means that the earlier algebraists we know of … all had expressed their equations mostly in ...

SIAM Journal on Numerical Analysis, Vol. 27, No. 3 (Jun., 1990), pp. 704-735 (32 pages) Ordinary differential equations can be recast into a nonlinear canonical form called an S-system. Evidence for ...

Geometric partial differential equations of level-set form are usually constructed by a variational method using either Dirac delta function or co-area formula in the energy functional to be minimized ...