Bilinear

In mathematics, an algebra over a field is a vector space equipped with a bilinear product.

The function f(x,y)#61;xy is bilinear, because f(ax#43;bu,y)#61;af(x,y)#43;bf(u,y) and f(x,ay#43;bv)#61;af(x,y)#43;bf(x,v) for all values.

bilinear isotropic hardening