An arithmetic expression is an expression that results in a numeric value. There are two kinds of numeric values, integers (whole numbers), and real or floating point numbers (numbers containing a decimal point).
Questions tagged [arithmetic-expressions]
677 questions
337
votes
24 answers
How do I use floating-point arithmetic in bash?
I am trying to divide two image widths in a Bash script, but bash gives me 0 as the result:
RESULT=$(($IMG_WIDTH/$IMG2_WIDTH))
I did study the Bash guide and I know I should use bc, in all examples in internet they use bc. In echo I tried to put…
Medya Gh
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248
votes
9 answers
Is there an exponent operator in C#?
For example, does an operator exist to handle this?
float Result, Number1, Number2;
Number1 = 2;
Number2 = 2;
Result = Number1 (operator) Number2;
In the past the ^ operator has served as an exponential operator in other languages, but in C# it…
Charlie
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225
votes
6 answers
How to use mod operator in bash?
I'm trying a line like this:
for i in {1..600}; do wget http://example.com/search/link $i % 5; done;
What I'm trying to get as output is:
wget http://example.com/search/link0
wget http://example.com/search/link1
wget…
Eric
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106
votes
14 answers
Is it possible to simplify (x == 0 || x == 1) into a single operation?
So I was trying to write the nth number in the Fibonacci sequence in as compact a function as possible:
public uint fibn ( uint N )
{
return (N == 0 || N == 1) ? 1 : fibn(N-1) + fibn(N-2);
}
But I'm wondering if I can make this even more…
user6048670
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74
votes
8 answers
What does the compiler do here: int a = b * (c * d * + e)?
I had a strange bug in my program, and after a few hours of debugging, I found the following very stupid line:
int a = b * (c * d * + e)
If you don't see it: Between d and e I wrote * +, where just a +was intended.
Why does this compile and what…
Michael
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67
votes
6 answers
Why does NaN^0 == 1
Prompted by a spot of earlier code golfing why would:
>NaN^0
[1] 1
It makes perfect sense for NA^0 to be 1 because NA is missing data, and any number raised to 0 will give 1, including -Inf and Inf. However NaN is supposed to represent…
Simon O'Hanlon
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48
votes
3 answers
How do I add two integers together with Twisted?
I have two integers in my program; let's call them "a" and "b". I would like to add them together and get another integer as a result. These are regular Python int objects. I'm wondering; how do I add them together with Twisted? Is there a…
Glyph
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48
votes
1 answer
How to multiply/divide/add/subtract numbers of different types?
I'm working through the second edition of the Rust handbook, and decided to try and make the classic Celsius-to-Fahrenheit converter:
fn c_to_f(c: f32) -> f32 {
return ( c * ( 9/5 ) ) + 32;
}
Compiling this with cargo build will yield the…
Kenny Worden
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40
votes
7 answers
Prolog =:= operator
There are some special operators in Prolog, one of them is is, however, recently I came across the =:= operator and have no idea how it works.
Can someone explain what this operator does, and also where can I find a predefined list of such special…
nubela
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35
votes
2 answers
Is Python's == an equivalence relation on the floats?
In native Python, without using NumPy (for which numpy.nan != numpy.nan) there is no NaN, so am I right in thinking that Python's floating point == is reflexive? Then since it is symmetric (a == b implies b == a) and transitive (if a==b and b==c…
xnx
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32
votes
2 answers
bash: $[] vs. $(())
I have just stumbled upon the bash syntax:
foo=42
bar=$[foo+1] # evaluates an arithmetic expression
When I Googled for this, I found http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_03_04.html#sect_03_04_05:
3.4.6. Arithmetic…
Chen Levy
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30
votes
3 answers
How do promotion rules work when the signedness on either side of a binary operator differ?
Consider the following programs:
// http://ideone.com/4I0dT
#include
#include
int main()
{
int max = std::numeric_limits::max();
unsigned int one = 1;
unsigned int result = max + one;
std::cout <<…
Billy ONeal
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28
votes
2 answers
Ambiguous reference to member '=='
That must be a basic mistake, but I can't see what is wrong in this code:
.... object is some NSManagedObject ....
let eltType = ((object.valueForKey("type")! as! Int) == 0) ? .Zero : .NotZero
At compile time, I get this message:
Ambiguous…
Michel
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25
votes
3 answers
Subtraction between signed and unsigned followed by division
The following results make me really confused:
int i1 = 20-80u; // -60
int i2 = 20-80; // -60
int i3 =(20-80u)/2; // 2147483618
int i4 =(20-80)/2; // -30
int i5 =i1/2; // -30
i3 seems to be computed as (20u-80u)/2, instead of…
Leo Lai
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23
votes
4 answers
In R why is factorial(100) displayed differently to prod(1:100)?
In R I am finding some odd behaviour that I can't explain and I am hoping someone here can. I believe that the value of 100! is this big number.
A few lines from the console showing expected behaviour...
>factorial( 10 )
[1] 3628800
>prod( 1:10…
Simon O'Hanlon
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