integral competition HP50g vs. DM42

[Thomas Okken]

(08-24-2020 10:30 AM)peacecalc Wrote:  The algorithmus can be a kind of gaussian quadrature, because that one doesn't use the limits on the left and right side.

Romberg and other method use the limits of the integration aera.

Free42 uses are modified Romberg method that doesn't use the endpoints. The code was originally written by Hugh Steers; this comment is from core_math1.cc:

Code:


/* approximate integral of `f' between `a' and `b' subject to a given
 * error. Use Romberg method with refinement substitution, x = (3u-u^3)/2
 * which prevents endpoint evaluation and causes non-uniform sampling.
 */