DiracDelta はディラックのデルタ関数またはインパルス関数
Heaviside は階段関数またはステップ関数と呼ばれるものです。
>>> import sympy as sp >>> s, t = sp.symbols('s, t') >>> a = sp.symbols('a', real=True) >>> sp.laplace_transform(sp.DiracDelta(t), t, s) (1 - Heaviside(0), -oo, True) >>> sp.inverse_laplace_transform(1, s, t) DiracDelta(t) >>> sp.laplace_transform(sp.Heaviside(t), t, s) (1/s, 0, True) >>> sp.inverse_laplace_transform(1/s, s, t) Heaviside(t) >>> sp.laplace_transform(sp.exp(-t*a)*sp.Heaviside(t), t, s) (1/(a + s), 0, Abs(arg(a)) <= pi/2) >>> sp.inverse_laplace_transform(1/(s+a), s, t) exp(-a*t)*Heaviside(t)