Rounding issue when dealing with Radian Angles and Distance. c++ - c++

Question

Noob Here.
I have a problem where I have to round my outputs to 4 decimal places and I'm getting weird return values.
I'm using this with all variables being double or int since precision is secondary to getting it to work semi-accurately.
//Rounds Input to 4 decimal places
double round(double initial)
{
int newInitial = (initial * 10000);
double round = newInitial / 10000;
return round;
}
This returns values along the lines of 0.781623...-1311 & 2.25194111-3
I have to find 2 things, a Positive radian angle for "vectorC" and Distance saved going from the Origin of a Coordinate plane by following one direct vectorC over the the path created by 2 others, vectorA
+vectorB.
Initially I was getting this problem with my function that finds the radian angle here:
/*Finds Positive Radian Angle of Vector C by using inverse tangent given x and y dimensions. Using Pi at 11 decimals.
*/
double angle(int x2,int y2)
{
double pi = 3.14159265359;
double vAngle = atan(y2 / x2);
if (x2 < 0 && y2 > 0)
{
vAngle = pi + vAngle;
}
if (x2 < 0 && y2 < 0)
{
vAngle = pi + vAngle;
}
if (x2 < 0 && y2 < 0)
{
vAngle = (2 * pi) + vAngle;
}
return vAngle;
}
I was thinking that its because of the decimal length being to long for double but I'm also getting this issue with my Distance function here:
//Uses distance formula to find the Magnitude of a "Vector" from Coordinates (x1,y1) to (x2,y2)
double distance(double x1,double y1,double x2,double y2)
{
double vDistance = sqrt((pow(x2 - x1, 2) + pow(y2 - y1, 2)));
return vDistance;
}
I'm kinda lost. I know the math is correct but my implementation is breaking somewhere. Any Help would be Great.
EDIT: OK so it seems my functions are breaking before the rounding even occurs.
Heres an Example. Lets say we have 3 points. (0,0)(1,1)(1,-3)
Vector A from (0,0)->(1,1) has distance sqrt(2) aprox ~ 1.4142
Vector B from (1,1)->(1,-3) has distance 2
Vector C from (0,0)->(1,-3) has distance sqrt(10) aprox ~ 3.1623
When using distance() to find the values it returns 1.4142143.16228-1, 3.16228 , 2111-3. So there's something wrong with either my distance function or the numbers passed but the numbers passed are whole number doubles. Dont know why the first answer is coming back as a number with 2 decimals
Then with my Angle function the Angle should be x=arctan(-3/1)=5.0341. Instead im getting just -1. I can post the entire program if needed.
EDIT2: So the Error is occuring before my rounding even occurs i'm thinking its cause im using double instead of float maybe?? I have two different functions and both print with a weird ending before i even pass them through my round function. Again using xy(0,0), v1xy(1,1), v2xy(1,-3)
//Uses distance formula to find the Magnitude of a "Vector" from Coordinates (x1,y1) to (x2,y2)
double distance(double x1,double y1,double x2,double y2)
{
double vDistance = sqrt((x2 - x1)*(x2 - x1) + (y2-y1)*(y2-y1));
return vDistance;
}
All three are printed out as:
cout << vectorA <<endl<< vectorB <<endl<< vectorC<<endl;
And the answers come out correctly for the first two but then the third comes out incorrect and with a -3 stuck on. Here:
https://gyazo.com/343ec1eaddb45cc7abd160ab7ac39a5d
Then commenting that out and just checking for Angle:
/*Finds Positive Radian Angle of Vector C by using inverse tangent given x and y dimensions. Using Pi at 11 decimals.
*/
double angle(int x2,int y2)
{
double pi = 3.14159265359;
double vAngle = atan(y2 / x2);
if (x2 < 0 && y2 > 0)
{
vAngle = pi + vAngle;
}
if (x2 < 0 && y2 < 0)
{
vAngle = pi + vAngle;
}
if (x2 < 0 && y2 < 0)
{
vAngle = (2 * pi) + vAngle;
}
return vAngle;
}
gives me a similar result:
https://gyazo.com/db19c0263a45543653e1d9549a4dd50b