Benutzer:MovGP0/Mathematica

Mathematica

Lists

Calculate the probability that a 6-sided dice gets a number less than 4:

ClearAll["Global`*"]
possible = {1, 2, 3, 4, 5, 6}
good = Select[possible, # < 4 &]
prob = Length[good] / Length[possible]

Apply and deconstruct

ClearAll["Global`*"]
circumfence = 12π
{radius} = r /. Solve[circumfence == 2*r*π, r]

Solve system of linear equations

ClearAll["Global`*"];
M = {{3, 0, 0}, 
     {1, 2, 0}, 
     {0, 1, 4}}
(* {{3, 0, 0}, {1, 2, 0}, {0, 1, 4}} *)
system = M.{cat, head, feet} == {30, 20, 9}
(* {3 cat, cat + 2 head, 4 feet + head} == {30, 20, 9} *)
result = Solve[system, {cat, head, feet}]
(* {{cat -> 10, head -> 5, feet -> 1}} *)
{cat, head, feet} = {cat, head, feet} /. result[[1]]
(* {10, 5, 1} *)
head + feet * cat
(* 15 *)

Cheatsheet

Assignments

a = 3;	assignment
a := 3;	delayed assignment
a == 3;	equality
a =.;	Clear[a]
a === true;	boolean test
f[x_] := f[x] = ...;	store computed value

Formatting

Ctrl+T	Exponent
Ctrl+,	Square Root
Ctrl+/	Horizontal Fraction
Ctrl+f	Form input

Text Formatting

Ctrl+ü	Underscript
Ctrl+q	Overscript
Ctrl+-	Index