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Slanted Line Integral

curvature
LM
1
MN
1
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skip the point M
show definitions
Generally speaking, the line integral of a function over a given curve is defined by selecting points on the curve, evaluating the function's values at these points, and then taking the limit of the evaluated expression as the number of selected points approaches infinity in an appropriate way.
The definition of the slanted line integral is of a different nature. The integration is performed over a domain on the left-hand side of the curve, which is bounded by the given curve and two lines which are parallel to the axes. Let
f:
2
be an integrable function and let
F:
2
be its cumulative distribution function,
F(x,y)=
y
v=0
x
u=0
f(u,v)dudv
. Let
LN
be a given continuous and tendable curve (i.e., its tendency is defined for all its interior points). Suppose that
LN
is uniformly tended (i.e., its tendency indicator vector is constant for all its interior points). Then the slanted line integral of
F
over
LN
is defined as follows:
(S)
LN
F
D
fdxdy-τ(LN)·F(C)+
1
2
[τ(L)·F(L)+τ(N)·F(N)]
,
where
D
is the positive domain of the curve (i.e., the domain bounded by
LN
and two lines that are parallel to the axes, such that
D
is on the left of
LN
),
τ(LN)
is the tendency of the uniformly tended curve
LN
, and
τ(L)
and
τ(N)
are the tendencies of the curve at the points
L
and
N
respectively. The letter
"S"
in the notation of the slanted line integral stands for "Slanted". The curve
LN
should be a subcurve of another curve
KLNO
, to assure that the tendencies at the points
L
and
N
are well defined. In case the curve
LN
is not uniformly tended (the tendency indicator vector at the subcurve
LM
is not equal to the tendency indicator vector at the subcurve
MN
), then the slanted line integral of
F
over
LN
is defined as the sum:
(S)
LN
F
(S)
LM
F+
(S)
MN
F
, where each of the integrals on the right is calculated as a slanted line integral over a uniformly tended curve.
In this Demonstration you can drag the points
K
,
L
,
M
,
N
,
O
, flip the orientation of the curve, or vary the curvature of the subcurves
LM
and
MN
to see how these changes affect each of the parameters in the definition of the slanted line integral.
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