Benford's law: Difference between revisions
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9: 4.50% | 4.58% | 0.0757%
</pre>
=={{header|ABC}}==
<syntaxhighlight lang="abc">HOW TO RETURN fibonacci.numbers n:
PUT 1, 1 IN a, b
PUT {} IN fibo
FOR i IN {1..n}:
INSERT a IN fibo
PUT b, a+b IN a, b
RETURN fibo
HOW TO RETURN digit.distribution nums:
PUT {} IN digits
FOR i IN {1..9}: PUT i IN digits["`i`"]
PUT {} IN dist
FOR i IN {1..9}: PUT 0 IN dist[i]
FOR n IN nums:
PUT digits["`n`"|1] IN digit
PUT dist[digit] + 1 IN dist[digit]
FOR i IN {1..9}:
PUT dist[i] / #nums IN dist[i]
RETURN dist
PUT digit.distribution fibonacci.numbers 1000 IN observations
WRITE "Digit"<<6, "Expected">>10, "Observed">>10/
FOR d IN {1..9}:
WRITE d<<6, ((10 log (1 + 1/d))>>10)|10, observations[d]>>10/</syntaxhighlight>
{{out}}
<pre>Digit Expected Observed
1 0.30102999 0.301
2 0.17609125 0.177
3 0.12493873 0.125
4 0.09691001 0.096
5 0.07918124 0.08
6 0.06694678 0.067
7 0.05799194 0.056
8 0.05115252 0.053
9 0.04575749 0.045</pre>
=={{header|Ada}}==
Line 247 ⟶ 285:
8 1003 490.7 10.46 5.12 5.34
9 1006 438.9 10.49 4.58 5.91</pre>
=={{header|Aime}}==
<syntaxhighlight lang="aime">text
Line 403 ⟶ 442:
Benford: 0.046 actual: 0.045
</pre>
=={{header|APL}}==
{{works with|Dyalog APL}}
<syntaxhighlight lang="apl">task←{
benf ← ≢÷⍨(⍳9)(+/∘.=)(⍎⊃∘⍕)¨
fibs ← (⊢,(+/¯2↑⊢))⍣998⊢1 1
exp ← 10⍟1+÷⍳9
obs ← benf fibs
⎕←'Expected Actual'⍪5⍕exp,[1.5]obs
}</syntaxhighlight>
{{out}}
<pre>Expected Actual
0.30103 0.30100
0.17609 0.17700
0.12494 0.12500
0.09691 0.09600
0.07918 0.08000
0.06695 0.06700
0.05799 0.05600
0.05115 0.05300
0.04576 0.04500</pre>
=={{header|Arturo}}==
Line 798 ⟶ 861:
9 : 4.5 % 4.58 %
</pre>
=={{header|Chipmunk Basic}}==
{{trans|Yabasic}}
{{works with|Chipmunk Basic|3.6.4}}
<syntaxhighlight lang="vbnet">100 cls
110 n = 1000
120 dim actual(n)
130 for nr = 1 to n
140 num$ = str$(fibonacci(nr))
150 j = val(left$(num$,1))
160 actual(j) = actual(j)+1
170 next
180 print "First 1000 Fibonacci numbers"
190 print "Digit Actual freq Expected freq"
200 for i = 1 to 9
210 freq = frequency(i)*100
220 print format$(i,"###");
230 print using " ##.###";actual(i)/10;
240 print using " ##.###";freq
250 next
260 end
270 sub frequency(n)
280 frequency = (log10(n+1)-log10(n))
290 end sub
300 sub log10(n)
310 log10 = log(n)/log(10)
320 end sub
330 sub fibonacci(n)
335 rem https://rosettacode.org/wiki/Fibonacci_sequence#Chipmunk_Basic
340 n1 = 0
350 n2 = 1
360 for k = 1 to abs(n)
370 sum = n1+n2
380 n1 = n2
390 n2 = sum
400 next k
410 if n < 0 then
420 fibonacci = n1*((-1)^((-n)+1))
430 else
440 fibonacci = n1
450 endif
460 end sub</syntaxhighlight>
=={{header|Clojure}}==
<syntaxhighlight lang="lisp">(ns example
Line 1,645 ⟶ 1,751:
'''Comparison chart.''' The following function creates a chart, in order to compare the distribution of the first digis in a givel list or numbers, and the Benford distribution:
[[File:Fōrmulæ - Benford's law
'''Testing.''' Testing with the previous list of numbers:
Line 1,670 ⟶ 1,776:
[[File:Fōrmulæ - Benford's law 14.png]]
=={{header|FutureBasic}}==
<syntaxhighlight lang="futurebasic">
Short t, i, j, k, m
Double a(9), z
Double phi, psi
CFStringRef s
print @"Benford:"
for i = 1 to 9
a(i) = log10( 1 + 1 / i )
print fn StringWithFormat( @"%.3f ", a(i) ),
next
// Fibonacci according to DeMoivre and Binet
for t = 1 to 9 : a(t) = 0 : next // Clean array
phi = ( 1 + sqr(5) ) / 2
psi = ( 1 - sqr(5) ) / 2
for i = 1 to 1000
z = ( phi^i - psi^i ) / sqr( 5 )
s = fn StringWithFormat( @"%e", z) // Get first digit
t = fn StringIntegerValue( left( s, 1 ) )
a(t) = a(t) + 1
next
print @"\n\nFibonacci:"
for i = 1 to 9
print fn StringWithFormat( @"%.3f ", a(i) / 1000 ),
next
// Multiplication tables
for t = 1 to 9 : a(t) = 0 : next // Clean array
for i = 1 to 10
for j = 1 to 10
for k = 1 to 10
for m = 1 to 10
z = i * j * k * m
s = fn StringWithFormat( @"%e", z )
t = fn StringIntegerValue( left( s, 1 ) )
a(t) = a(t) + 1
next
next
next
next
print @"\n\nMultiplication:"
for i = 1 to 9
print fn StringWithFormat( @"%.3f ", a(i) / 1e4 ),
next
// Factorials according to DeMoivre and Stirling
for t = 1 to 9 : a(t) = 0 : next // Clean array
for i = 10 to 110
z = sqr(2 * pi * i ) * (i / exp(1) )^i
s = fn StringWithFormat( @"%e", z )
t = fn StringIntegerValue( left( s, 1 ) )
a(t) = a(t) + 1
next
print @"\n\nFactorials:"
for i = 1 to 9
print fn StringWithFormat( @"%.2f ", a(i) / 100 ),
next
handleevents
}</syntaxhighlight>
{{Out}}
<pre>
Benford:
0.301 0.176 0.125 0.097 0.079 0.067 0.058 0.051 0.046
Fibonacci:
0.301 0.177 0.125 0.096 0.080 0.067 0.056 0.053 0.045
Multiplication:
0.302 0.181 0.124 0.103 0.071 0.061 0.055 0.055 0.047
Factorials:
0.35 0.16 0.12 0.06 0.06 0.06 0.02 0.10 0.08
</pre>
=={{header|Go}}==
Line 2,360 ⟶ 2,549:
8 0.053 0.0511525
9 0.045 0.0457575</pre>
=={{header|MATLAB}}==
{{trans|Julia}}
<syntaxhighlight lang="MATLAB">
benfords_law();
function benfords_law
% Benford's Law
P = @(d) log10(1 + 1./d);
% Benford function
function counts = benford(numbers)
firstdigit = @(n) floor(mod(n / 10^floor(log10(n)), 10));
counts = zeros(1, 9);
for i = 1:length(numbers)
digit = firstdigit(numbers(i));
if digit ~= 0
counts(digit) = counts(digit) + 1;
end
end
counts = counts ./ sum(counts);
end
% Generate Fibonacci numbers
function fibNums = fibonacci(n)
fibNums = zeros(1, n);
a = 0;
b = 1;
for i = 1:n
c = b;
b = a + b;
a = c;
fibNums(i) = b;
end
end
% Sample
sample = fibonacci(1000);
% Observed and expected frequencies
observed = benford(sample) * 100;
expected = arrayfun(P, 1:9) * 100;
% Table
mytable = [1:9; observed; expected]';
% Plotting
bar(1:9, observed);
hold on;
plot(1:9, expected, 'LineWidth', 2);
hold off;
title("Benford's Law");
xlabel("First Digit");
ylabel("Frequency %");
legend("1000 Fibonacci Numbers", "P(d) = log10(1 + 1/d)");
xticks(1:9);
% Displaying the results
fprintf("Benford's Law\nFrequency of first digit\nin 1000 Fibonacci numbers\n");
disp(table(mytable(:,1),mytable(:,2),mytable(:,3),'VariableNames',{'digit', 'observed(%)', 'expected(%)'}))
end
</syntaxhighlight>
{{out}}
<pre>
Benford's Law
Frequency of first digit
in 1000 Fibonacci numbers
digit observed(%) expected(%)
_____ ___________ ___________
1 30 30.103
2 17.7 17.609
3 12.5 12.494
4 9.6 9.691
5 8 7.9181
6 6.7 6.6947
7 5.7 5.7992
8 5.3 5.1153
9 4.5 4.5757
</pre>
=={{header|NetRexx}}==
<syntaxhighlight lang="netrexx">/* NetRexx */
Line 3,878 ⟶ 4,149:
8 0.05115 0.06646 0.01531
9 0.04576 0.05831 0.01255</pre>
=={{header|SETL}}==
<syntaxhighlight lang="setl">program benfords_law;
fibos := fibo_list(1000);
expected := [log(1 + 1/d)/log 10 : d in [1..9]];
actual := benford(fibos);
print('d Expected Actual');
loop for d in [1..9] do
print(d, ' ', fixed(expected(d), 7, 5), ' ', fixed(actual(d), 7, 5));
end loop;
proc benford(list);
dist := [];
loop for n in list do
dist(val(str n)(1)) +:= 1;
end loop;
return [d / #list : d in dist];
end proc;
proc fibo_list(n);
a := 1;
b := 1;
fibs := [];
loop while n>0 do
fibs with:= a;
[a, b] := [b, a+b];
n -:= 1;
end loop;
return fibs;
end proc;
end program;</syntaxhighlight>
{{out}}
<pre>d Expected Actual
1 0.30103 0.30100
2 0.17609 0.17700
3 0.12494 0.12500
4 0.09691 0.09600
5 0.07918 0.08000
6 0.06695 0.06700
7 0.05799 0.05600
8 0.05115 0.05300
9 0.04576 0.04500</pre>
=={{header|Sidef}}==
<syntaxhighlight lang="ruby">var (actuals, expected) = ([], [])
var fibonacci = 1000.of {|i| fib(i).digit(
for i in (1..9) {
var num = fibonacci.count_by {|j| j == i }
actuals.append(num / 1000)
Line 3,889 ⟶ 4,204:
"%17s%17s\n".printf("Observed","Expected")
for i in (1..9) {
"%d : %11s %%%15s %%\n".printf(
i, "%.2f".sprintf(100 * actuals[i - 1]),
Line 3,895 ⟶ 4,211:
)
}</syntaxhighlight>
{{out}}
<pre>
Line 3,909 ⟶ 4,224:
9 : 4.50 % 4.58 %
</pre>
=={{header|SQL}}==
If we load some numbers into a table, we can do the sums without too much difficulty. I tried to make this as database-neutral as possible, but I only had Oracle handy to test it on.
Line 4,212 ⟶ 4,528:
9 | 4.50% | 4.58%
</pre>
=={{header|True BASIC}}==
{{trans|Chipmunk Basic}}
<syntaxhighlight lang="qbasic">FUNCTION log10(n)
LET log10 = LOG(n)/LOG(10)
END FUNCTION
FUNCTION frequency(n)
LET frequency = (log10(n+1)-log10(n))
END FUNCTION
FUNCTION fibonacci(n)
!https://rosettacode.org/wiki/Fibonacci_sequence#True_BASIC
LET n1 = 0
LET n2 = 1
FOR k = 1 TO ABS(n)
LET sum = n1+n2
LET n1 = n2
LET n2 = sum
NEXT k
IF n < 0 THEN LET fibonacci = n1*((-1)^((-n)+1)) ELSE LET fibonacci = n1
END FUNCTION
CLEAR
LET n = 1000
DIM actual(0)
MAT REDIM actual(n)
FOR nr = 1 TO n
LET num$ = STR$(fibonacci(nr))
LET j = VAL((num$)[1:1])
LET actual(j) = actual(j)+1
NEXT nr
PRINT "First 1000 Fibonacci numbers"
PRINT "Digit Actual freq Expected freq"
FOR i = 1 TO 9
LET freq = frequency(i)*100
PRINT USING "###": i;
PRINT USING " ##.###": actual(i)/10;
PRINT USING " ##.###": freq
NEXT i
END</syntaxhighlight>
=={{header|VBA (Visual Basic for Application)}}==
<syntaxhighlight lang="vb">
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