some math and random function's

[bluatigro]

this can be useful

atan2() can have error


''bluatigro 26 apr 2018
''math module
''needs :
''as global const :
''pi = atn( 1 ) * 4

function rad( deg )
''from degrees to radians
 rad = deg * pi / 180
end function

function degrees( r )
''from radians to degrees
 degrees = r * 180 / pi
end function

sub rotate byref k , byref l , deg
 s = sin( rad( deg ) )
 c = cos( rad( deg ) )
 hk = k * c - l * s
 hl = k * s + l * c
 k = hk
 l = hl
end sub

function atan2( x , y )
''this i am not sure about
 if y = 0 then
   if x > 0 then
     angle = pi / 2
   else
     if x < 0 then
       angle = 0 - pi / 2
     else
       atan2 = 20
       exit function
     end if
   end if
 end if
 if x < 0 then
   angle = atn( x / y ) + pi
 else
   angle = atn( x / y )
 end if
 if angle < 0-pi then
   angle = angle + pi * 2
 end if
 if angle > pi then
   angle = angle - pi * 2
 end if
 atan2 = angle
end function

sub nr.swap byref a , byref b
 h = a
 a = b
 b = h
end

sub str.swap byref a$ , byref b$
 h$ = a$
 a$ = b$
 b$ = c$
end sub

function rnd.range( low , high )
 rnd.range = rnd(0) * ( high - low ) + low
end function

function rnd.int( low , high )
 rnd.int = int( rnd.range( low , high + 1 ) )
end function

function rnd.normal( mean , d )
 rnd.normal = sqr( abs( 2 * log( rnd(0) ) ) _
 * cos( rnd(0) * rnd.pi * 2 ) * d + mean
end function

function rnd.exp( mean )
 rnd.exp = log( rnd(0) ) * mean
end function