liblogintpack.h

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#ifndef liblogintpack_h
#define liblogintpack_h

#include <cmath>

namespace logintpack
{
        int8_t pack8logCeil(double x,double lmin, double lmax, uint8_t base=128)
        {
                if(base>128) base=128;
                float l =log(fabs(x));
                float centered = (l-lmin)/(lmax-lmin)*base;
                int8_t  r=ceil(centered);
                if(centered >= base-1) r=base-1;
                if(centered < 0) r=0;
                if(x<0) r=-r;
                return r;
        }

    int8_t pack8log(double x,double lmin, double lmax, uint8_t base=128)
    {
            if(base>128) base=128;
        float l =log(fabs(x));
        float centered = (l-lmin)/(lmax-lmin)*base;
        int8_t  r=centered;
        if(centered >= base-1) r=base-1;
        if(centered < 0) r=0;
        if(x<0) r=-r;
        return r;
    }

    int8_t pack8logClosed(double x,double lmin, double lmax, uint8_t base=128)
    {
            if(base>128) base=128;
        float l =log(fabs(x));
        float centered = (l-lmin)/(lmax-lmin)*(base-1);
        int8_t  r=round(centered);
        if(centered >= base-1) r=base-1;
        if(centered < 0) r=0;
        if(x<0) r=-r;
        return r;
    }


    double unpack8log(int8_t i,double lmin, double lmax, uint8_t base=128)
    {
            if(base>128) base=128;
            float basef=base;
        float l=lmin+abs(i)/basef*(lmax-lmin);
        float val=exp(l);
        if(i<0) return -val; else return val;
    }

    double unpack8logClosed(int8_t i,double lmin, double lmax, uint8_t base=128)
    {
            if(base>128) base=128;
            float basef=base-1;
        float l=lmin+abs(i)/basef*(lmax-lmin);
                if (abs(i) == base-1) l = lmax;
        float val=exp(l);
        if(i<0) return -val; else return val;
    }

}
#endif