$$ \newcommand{\uex}{{u_{\small\mbox{e}}}} \newcommand{\half}{\frac{1}{2}} \newcommand{\halfi}{{1/2}} \newcommand{\xpoint}{\boldsymbol{x}} \newcommand{\normalvec}{\boldsymbol{n}} \newcommand{\Oof}[1]{\mathcal{O}(#1)} \newcommand{\Ix}{\mathcal{I}_x} \newcommand{\Iy}{\mathcal{I}_y} \newcommand{\It}{\mathcal{I}_t} \newcommand{\setb}[1]{#1^0} % set begin \newcommand{\sete}[1]{#1^{-1}} % set end \newcommand{\setl}[1]{#1^-} \newcommand{\setr}[1]{#1^+} \newcommand{\seti}[1]{#1^i} \newcommand{\Real}{\mathbb{R}} $$
Operations on slices of arrays
Introductory example: compute \( d_i = u_{i+1}-u_i \)
n
=
u
.
size
for
i
in
range
(
0
, n
-1
): d[i]
=
u[i
+1
]
-
u[i]
Note: all the differences here are independent of each other.
Therefore \( d = (u_1,u_2,\ldots,u_n) - (u_0,u_1,\ldots,u_{n-1}) \)
In
numpy
code:
u[1:n] - u[0:n-1]
or just
u[1:] - u[:-1]
