Use a define for '3' for example KELVINLET_MAX_ITERATIONS

use const for parameters that are not changed. This makes it easier for developer to understand and compilers to optimize.

it => num_iterations

Use more descriptive parameters for r_e, kvl, r. Currently you need to read the code and papers in order to understand what you need to pass.

for example it => num_iterations, r => radius.

use pow2f

use pow2f and pow3f

use pow2f

use pow3f

add const where applicable.

more descriptive names

add const

same

same

const

const

pow2f also in the next 4 lines

use typedef to define the function pointer

use floats

const

const, pow2f

const, pow3f

pow2f, pow5f (needs to be added to math base)

const, pow2f, pow3f, pow5f

you got the drill :-)

this is pow6f, use pow4f(x) * x