30
votes
How to enter a repeating decimal in Mathematica
Indeed, there is no direct method to input a repeating decimal. The closest you can get is to input the repeating digits into FromDigits[]:
$$0.\overline{142857}$$
<...
23
votes
Accepted
Puzzle with Mathematica
A non brute-force approach is the following, similar to my answer for the Zebra Puzzle.
Both puzzles are examples of constrainst satisfaction problems, that can be solved with ...
- 7,043
16
votes
How to enter a repeating decimal in Mathematica
Use the ResourceFunction RepeatingDecimalToRational:
...
- 149k
14
votes
Puzzle with Mathematica
Can't think out a better method than brute force, it'll be conciser in Mathematica of course:
...
- 62.9k
13
votes
Arithmetic operations on NumericArrays
It seems like no one answered this yet, so let me elaborate a little on my comment. A simple example of using FunctionCompile to add ...
- 21.6k
12
votes
How to recover Pauli matrices properties in Mathematica?
The Pauli vector:
σ = Table[PauliMatrix[i], {i, 1, 3}]
MatrixForm /@ σ
One can define a dot product of matrices (in spaces of arbitrary dimension):
...
- 23.6k
12
votes
Accepted
Trace of -{1} expression
This is a good question for uncovering an important difference between listability and vectorization. Sometimes these terms are used interchangeably, but I would like to make a technical distinction. ...
- 233k
11
votes
Puzzle with Mathematica
To make the brute force solution a bit more pleasant for the eye of the observer:
...
9
votes
Arbitrary-Precision Arithmetic behaves unexpectedly
This is at best a partial answer.
I don't know in full detail what is going on with FullForm or InputForm but I will venture to ...
9
votes
9
votes
Accepted
Why am I seeing what looks like a violation of operator precedence?
Consider the following:
2.84852`+3
2.85
This syntax means "write 2.84852 with 3 digits ...
- 69.8k
9
votes
Why does the Mathematica give different numerical results?
They are supposed to be different.
(-y)^a /. a -> 2.99 /. y -> -2
(*7.94474*)
is equivalent to
2^2.99
or
...
- 7,907
8
votes
Product of elements of a list
Why is there no equivalent of Total for products?
There isn't an equivalent of Total for products, and I believe that there is ...
- 232k
8
votes
Accepted
multiply two vectors, component by component
No need to do anything fancy. This is just how ordinary list multiplication works:
{a1, a2, a3} {b1, b2, b3}
yields
...
- 13.6k
8
votes
Rounding Real number
You can use Round and specify the second argument,
t = {75.34123, 80.567, 85.789};
Round[t, 0.01]
(* {75.34, 80.57, 85.79} *)
...
- 5,864
7
votes
Accepted
How to form subgraphs from a connected graph
Update:
I just noticed this comment:
The constraint I have is: a node can not be in two subgraphs.
This is contradictory with the rest of the problem description:
need to find all possible ...
- 232k
7
votes
Accepted
Why Divide does not give the same answer?
First, since the precedence of Divide is higher than Times, you should expect to parse ...
- 129k
7
votes
Accepted
7
votes
Accepted
Does Mathematica simplify calculation when encounter zero?
A quick experiment shows it does not stop, but it will evaluates all expressions on RHS, even if one is zero.
...
- 135k
7
votes
Accepted
Simplify expressions with modulo 2 (Boolean algebra)
You are working in a Boolean algebra (this should be stated explicitly). So there are reduction relations. We'll compute those first.
...
- 58.2k
6
votes
intermediate steps of a Mathematica operation
I feel like I should be prefacing this answer with three confessions, considering that this is an arithmetic question. First, I had a hard time with the multiplication tables until I was nine years ...
6
votes
Accepted
Why does this whole number have a recurring value?
It's a numerical artifact that is due to finite precision of computer calculations. Indeed, when one computes
SetAccuracy[12.30*12, 15]
147.60000000000002
It'...
- 23.6k
6
votes
Accepted
Multiplication non-deterministic?
It's not a bug and it's not so uncommon. For an explanation have a look here. This and some related issues also appear in this MathGroup thread.
Also relevant: 1 2.
- 58.2k
6
votes
Is there a difference between Divide[a,b] and a/b?
I have just a little to add to @Szabolcs' answer, and this seemed an appropriate place rather than a separate Q&A. Since there is a theorem involved (see below), it should be pointed out that this ...
- 233k
6
votes
Insert $+$, $-$, $\times$, $/$, $($, $)$ into $123456789$ to make it equal to $100$
Similar to whuber's answer, we can use Groupings(introduced in version 11) to simplify the generation patterns, the number of patterns is related to the CatalanNumber, and use parallel computing, ...
- 15k
6
votes
Countdown arithmetic solver
Improved answer
(Since the contents of the original answer is contained in what follows here, the original answer is deleted.)
I address the following problem: given a set of numbers and a target, ...
- 10.1k
6
votes
Accepted
6
votes
Improving Map Function on Lists
A slightly faster method uses KroneckerProduct to create a suitable matrix of offsets. Some data:
...
- 129k
6
votes
Applying Mod on list of list with outcomes +1, -1, other
You can use -1 as the third argument of Mod:
Mod[##, -1] & @@@ lis
{-1, -1, 1, 2}
...
- 378k
6
votes
Solving calculation puzzle
Here are all $4$ solutions to the puzzle
Technique #1
heavily plagiarizing this excellent answer
Apparently Groupings is the tool for the job!
...
- 7,349
Only top scored, non community-wiki answers of a minimum length are eligible