number_solvelinmod Number Conversion

Number >> Number > number_ulamspiral

number_ulamspiral

Returns the Ulam spiral.

Calling Sequence

m = number_ulamspiral ( n )
m = number_ulamspiral ( n , keepall )

Parameters

n :

a 1-by-1 matrix of floating point integers, must be odd and greater than 1

keepall :

a 1-by-1 matrix of booleans, set to %t to keep all integers, set to %f to keep only primes (default keep=%f)

m :

a n-by-n matrix of floating point integers

Description

Returns the Ulam spiral.

Examples

number_ulamspiral ( 7 )
number_ulamspiral ( 7 , %t )
number_ulamspiral ( 9 )
number_ulamspiral ( 9 , %t )

// Plot the Ulam spiral
m=number_ulamspiral(301);
[i,j]=find(m>0);
plot(i,j,"b.")
h = gce();
h.children.mark_size=1;

Authors

Bibliography

http://en.wikipedia.org/wiki/Ulam_spiral

number_solvelinmod Number Conversion