Get theta from given spiral lengths
solve_theta_from_spiral_length.RdGet theta from given spiral lengths
solve_theta_from_spiral_length(len, interval = NULL, offset = 0)Arguments
- len
A vector of spiral lengths.
- interval
Interval to search for the solution.
- offset
Offset of the spiral. In the general form:
r = a + r*theta, offset is the value ofa.
Details
The length of the spiral has a complicated form, see https://downloads.imagej.net/fiji/snapshots/arc_length.pdf .
Let's say the form is l = f(theta), solve_theta_from_spiral_length tries to find theta by a known l.
It uses uniroot to search solutions.
Value
The theta value.
Examples
spiral_initialize()
s = current_spiral()
theta = pi*seq(2, 3, length = 10)
len = s$spiral_length(theta)
solve_theta_from_spiral_length(len) # should be very similar as theta
#> [1] 6.283185 6.632251 6.981317 7.330383 7.679445 8.028513 8.377580 8.726646
#> [9] 9.075712 9.424782