astIntersect

Find the point of intersection between two geodesic curves

Description:

This function finds the coordinate values at the point of intersection between two geodesic curves. Each curve is specified by two points on the curve. It can only be used with 2-dimensional Frames.

For example, in a basic Frame, it will find the point of intersection between two straight lines. But for a SkyFrame it will find an intersection of two great circles.

Synopsis

void astIntersect( AstFrame this, const double a1[2], const double a2[2], const double b1[2], const double b2[2], double cross[2] )

Parameters:

this
Pointer to the Frame.
a1
An array of double, with one element for each Frame axis (Naxes attribute). This should contain the coordinates of the first point on the first geodesic curve.
a2
An array of double, with one element for each Frame axis (Naxes attribute). This should contain the coordinates of a second point on the first geodesic curve. It should not be co-incident with the first point.
b1
An array of double, with one element for each Frame axis (Naxes attribute). This should contain the coordinates of the first point on the second geodesic curve.
b2
An array of double, with one element for each Frame axis (Naxes attribute). This should contain the coordinates of a second point on the second geodesic curve. It should not be co-incident with the first point.
cross
An array of double, with one element for each Frame axis in which the coordinates of the required intersection will be returned.

Notes: