[pygame] help with float issue

[nick2003 <nicholaskomsa@xxxxxxxxxxx>]

So in my game I have the character move 0.1 per tick. The problem is that
when i calculate the distance to the destination, the results seem all out
of wack when distance < 0.
heres my results:
moved. distance from destination,(208, 321)=1.03817816236 velocity: 0.1
distance from old pos: 0.1
moved. distance from destination,(208, 321)=0.943491350926 velocity: 0.1
distance from old pos: 0.1
moved. distance from destination,(208, 321)=0.850022330142 velocity: 0.1
distance from old pos: 0.1
moved. distance from destination,(208, 321)=0.758221599671 velocity: 0.1
distance from old pos: 0.1
moved. distance from destination,(208, 321)=0.668776514745 velocity: 0.1
distance from old pos: 0.1
moved. distance from destination,(208, 321)=0.582772733699 velocity: 0.1
distance from old pos: 0.1
moved. distance from destination,(208, 321)=0.501982162641 velocity: 0.1
distance from old pos: 0.1
moved. distance from destination,(208, 321)=0.429357804259 velocity: 0.1
distance from old pos: 0.1
moved. distance from destination,(208, 321)=0.36974336579 velocity: 0.1
distance from old pos: 0.1
moved. distance from destination,(208, 321)=0.330260789397 velocity: 0.1
distance from old pos: 0.1
------->moved. distance from destination,(208, 321)=0.31848739611 velocity:
0.1 distance from old pos: 0.1
------->moved. distance from destination,(208, 321)=0.337337003527 velocity:
0.1 distance from old pos: 0.1
moved. distance from destination,(208, 321)=0.382306534624 velocity: 0.1
distance from old pos: 0.1

You can see that where I inserted arrows, the distance instead of going to
0.2 or 0.1 it skips over the destination and goes to 0.38. I dont see how
this is possible since the distance from the old position is always 0.1

here is my code:


	def updateVelocity(self):
		'''calculates the velocity/movement to be done on x and y during move
method'''
		#update velocity
		vx = math.cos( self.heading )* self.speed
		vy = math.sin( self.heading )* self.speed 

		self.velocity = (vx , vy )

	def move(self ):

		d = math.sqrt ( (self.pos[0] - self.destination[0])**2 + (self.pos[1] -
self.destination[1])**2)
		v= math.sqrt( self.velocity[0]**2+ self.velocity[1]**2 )

		if d <=self.speed: #this does not work because the d rarely goes below 0.3
			self.pos = self.destination 
		else:
			self.oldpos = self.pos
			self.pos = ( self.pos[0] + self.velocity[0], self.pos[1] +
self.velocity[1] )
			d2 = math.sqrt ( (self.pos[0] - self.oldpos[0])**2 + (self.pos[1] -
self.oldpos[1])**2)
			print "moved. distance from destination," + str( (self.destination[0],
self.destination[1])) +"=" + str(d ) + " velocity: " + str(v) + " distance
from old pos: " + str(d2)










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