diff options
Diffstat (limited to 'lib/vector.py')
| -rw-r--r-- | lib/vector.py | 34 |
1 files changed, 31 insertions, 3 deletions
diff --git a/lib/vector.py b/lib/vector.py index 7323c92..5d26161 100644 --- a/lib/vector.py +++ b/lib/vector.py @@ -198,9 +198,6 @@ def rotate_around(x, y, z, u, v, w, theta, degrees=True): if degrees: theta = np.deg2rad(theta) - u2 = u**2 - v2 = v**2 - w2 = w**2 costheta = np.cos(theta) sintheta = np.sin(theta) icostheta = 1.0 - costheta @@ -211,3 +208,34 @@ def rotate_around(x, y, z, u, v, w, theta, degrees=True): Z = (-w*det)*icostheta + z*costheta + (-v*x + u*y)*sintheta return X, Y, Z + + +def equal_area_proj(x, y, z): + """ + Transform the coordinates to a 2-dimensional plane using the + Lambert azimuthal equal-area projection. + + Parameters + ---------- + x, y, z : scalars or 1-D arrays + The input vectors + + Returns + ------- + X, Y : tuple of scalars or arrays of the same length + + Notes + ----- + + .. math:: + + X = \sqrt{\frac{2}{1-z}}x + + .. math:: + + Y = \sqrt{\frac{2}{1-z}}y + """ + scale = np.sqrt(2.0 / (1.0 - z)) + X = scale * x + Y = scale * y + return X, Y |