private Envelope GetEnvelope(LinearFunction[] functions, EnvelopeKind kind)
{
Envelope envelope = null;
if (functions != null && functions.Length > 0)
{
int firstFunctionIndex, lastFunctionIndex, functionsIterationStep;
//While looking for upper envelope we will go from first to last function
if (kind == EnvelopeKind.Upper)
{
firstFunctionIndex = 0;
lastFunctionIndex = functions.Length - 1;
functionsIterationStep = 1;
}
//While looking for lower envelope we will go from last to first function
else
{
firstFunctionIndex = functions.Length - 1;
lastFunctionIndex = 0;
functionsIterationStep = -1;
}
List <LinearFunction> lines = new List <LinearFunction>();
List <CartesianCoordinates> points = new List <CartesianCoordinates>();
//We set the first line in the envelope
LinearFunction previousLine = functions[firstFunctionIndex];
lines.Add(previousLine);
//And calculate "theoretical" furthest to left point
points.Add(new CartesianCoordinates(_leftBorder, previousLine.Evaluate(_leftBorder)));
//We will look for intersection points between the functions
for (int i = firstFunctionIndex + functionsIterationStep; (kind == EnvelopeKind.Upper && i <= lastFunctionIndex) || (kind == EnvelopeKind.Lower && i >= lastFunctionIndex); i += functionsIterationStep)
{
LinearFunction currentLine = functions[i];
//Because we have taken intercept into consideration while sorting we can skip parallel lines
if (currentLine.Slope != previousLine.Slope)
{
//We add an intersection between previous and current line to the points collection
points.Add(previousLine.Intersect(currentLine).Value);
//If the latest intersection point lies before any of the previous one, we need to update those intersections to find the actual last intersection
int lastIntersectionIndex = points.Count - 1;
while (points[lastIntersectionIndex].X < points[lastIntersectionIndex - 1].X)
{
//Calculate the intersection between current on previous line
points[lastIntersectionIndex - 1] = lines[lastIntersectionIndex - 2].Intersect(currentLine).Value;
//Remove the no longer valid intersection and line
points.RemoveAt(lastIntersectionIndex);
lines.RemoveAt(lastIntersectionIndex - 1);
lastIntersectionIndex--;
}
//We add current line to the lines collection
previousLine = currentLine;
lines.Add(previousLine);
}
}
//We calculate "theoretical" furthest to right point
points.Add(new CartesianCoordinates(_rightBorder, previousLine.Evaluate(_rightBorder)));
envelope = new Envelope(lines.ToArray(), points.ToArray());
}
return(envelope);
}
public void ReturnTheSameValue(double value)
{
var result = linearFunction.Evaluate(value);
Assert.Equal(result, value);
}
