I try to use Oklab color space with original cpp header file. My code :

#include <cstdlib> // malloc
#include <cfloat>
#include <cmath> // -lm
#include <cstdio> // printf
#include "ok_color.h" //  ok_color.h : Oklab color space. A perceptual color space for image processing by 2021 Björn Ottosson

using namespace ok_color;

int main(void){

    struct Lab c;
    c.L = 100.0f;
    c.a = 0.0f;
    c.b = 0.0f;
    
    
    
    struct RGB rgb;
    rgb =  oklab_to_linear_srgb(c); 
    
    //
    printf("LAB : L = %.16f a = %.16f b = %.16f\n", c.L, c.a, c.b);
    printf("RGB : r = %.16f g = %.16f b = %.16f\n", rgb.r, rgb.g, rgb.b);
    return 0; 
}

I compile it and run

 g++ o.cpp -Wall -lm
./a.out

The result is :

LAB : L = 100.0000000000000000 a = 0.0000000000000000 b = 0.0000000000000000
RGB : r = 1000000.1875000000000000 g = 1000000.1250000000000000 b = 999999.93750

It is different then expected ( checked with Lch and Lab colour and gradient picker ) : rgb(255,255,255)

How should I do it ?