Runtime: implement new runtime for floats operation ..

[hhugo]

if/when ocaml/ocaml#944 is merged

[hhugo]

natively supported

cbrt
log2
acosh
asinh
atanh

other

exp2(x) => pow(2,x)

erf => https://hewgill.com/picomath/javascript/erf.js.html

function erf(x) {
    // constants
    var a1 =  0.254829592;
    var a2 = -0.284496736;
    var a3 =  1.421413741;
    var a4 = -1.453152027;
    var a5 =  1.061405429;
    var p  =  0.3275911;

    // Save the sign of x
    var sign = 1;
    if (x < 0) {
        sign = -1;
    }
    x = Math.abs(x);

    // A&S formula 7.1.26
    var t = 1.0/(1.0 + p*x);
    var y = 1.0 - (((((a5*t + a4)*t) + a3)*t + a2)*t + a1)*t*Math.exp(-x*x);

    return sign*y;
}

erfc => erfc ⁡ ( x ) = 1 − erf ⁡ ( x )

[hhugo]

needed for #1106

[hhugo]

Here is the list of primitives to implement

caml_acosh_float
caml_asinh_float
caml_atanh_float
caml_cbrt_float
caml_erf_float
caml_erfc_float
caml_exp2_float
caml_fma_float
caml_log2_float

[pmwhite]

I'm going to work on this.

[hhugo]

@pmwhite, no rush but what's your timeframe for working on this ?

[pmwhite]

@hhugo I expect to have a PR open by end-of-week, if not today.