Ejemplo n.º 1
0
void fexp(_MIPD_ flash x,flash y)
{ /* calculates y=exp(x) */
    int i,n,nsq,m,sqrn,op[5];
    BOOL minus,rem;
#ifdef MR_OS_THREADS
    miracl *mr_mip=get_mip();
#endif
    if (mr_mip->ERNUM) return;
    if (size(x)==0)
    {
        convert(_MIPP_ 1,y);
        return;
    }
    copy(x,y);

    MR_IN(54)

    minus=FALSE;
    if (size(y)<0)
    {
        minus=TRUE;
        negify(y,y);
    }
    ftrunc(_MIPP_ y,y,mr_mip->w9);
    n=size(y);
    if (n==MR_TOOBIG)
    {
        mr_berror(_MIPP_ MR_ERR_FLASH_OVERFLOW);
        MR_OUT
        return;
    }
Ejemplo n.º 2
0
static int norm(_MIPD_ int type,flash y)
{ /* convert y to first quadrant angle *
   * and return sign of result         */
    int s;
#ifndef MR_GENERIC_MT
    miracl *mr_mip=get_mip();
#endif
    if (mr_mip->ERNUM) return 0;
    s=PLUS;
    if (size(y)<0)
    {
        negify(y,y);
        if (type!=COS) s=(-s);
    }
    fpi(_MIPP_ mr_mip->pi);
    fpmul(_MIPP_ mr_mip->pi,1,2,mr_mip->w8);
    if (fcomp(_MIPP_ y,mr_mip->w8)<=0) return s;
    fpmul(_MIPP_ mr_mip->pi,2,1,mr_mip->w8);
    if (fcomp(_MIPP_ y,mr_mip->w8)>0)
    { /* reduce mod 2.pi */
        fdiv(_MIPP_ y,mr_mip->w8,mr_mip->w9);
        ftrunc(_MIPP_ mr_mip->w9,mr_mip->w9,mr_mip->w9);
        fmul(_MIPP_ mr_mip->w9,mr_mip->w8,mr_mip->w9);
        fsub(_MIPP_ y,mr_mip->w9,y);
    }
    if (fcomp(_MIPP_ y,mr_mip->pi)>0)
    { /* if greater than pi */
        fsub(_MIPP_ y,mr_mip->pi,y);
        if (type!=TAN) s=(-s);
    }
    fpmul(_MIPP_ mr_mip->pi,1,2,mr_mip->w8);
    if (fcomp(_MIPP_ y,mr_mip->w8)>0)
    { /* if greater than pi/2 */
        fsub(_MIPP_ mr_mip->pi,y,y);
        if (type!=SIN) s=(-s);
    }
    return s;
}
Ejemplo n.º 3
0
static BOOL act(int p,int q)
{ /* act on selected key */
    int k,n,c;
    aprint(PRESSED,4+5*p,6+3*q,keys[q][p]);
    switch(p+7*q)
    {
    case 0:  if (degrees) fmul(x,radeg,x);
             if (hyp) fsinh(x,x);
             else     fsin(x,x);
             newx=TRUE;
             break;
    case 1:  if (degrees) fmul(x,radeg,x);
             if (hyp) fcosh(x,x);
             else     fcos(x,x);
             newx=TRUE;
             break;
    case 2:  if (degrees) fmul(x,radeg,x);
             if (hyp) ftanh(x,x);
             else     ftan(x,x);
             newx=TRUE;
             break;
    case 3:  if (lgbase>0)
             {
                 n=size(x);
                 if (abs(n)<MR_TOOBIG)
                 {
                     convert(lgbase,x);
                     if (n<0) frecip(x,x);
                     fpower(x,abs(n),x);
                     newx=TRUE;
                     break;
                 }
                 if (lgbase==2)  fmul(x,loge2,x);
                 if (lgbase==10) fmul(x,loge10,x);
             }
             fexp(x,x);
             newx=TRUE;
             break;
    case 4:  mip->RPOINT=!mip->RPOINT;
             newx=TRUE;
             break;
    case 5:  clrall();
             newx=TRUE;
             break;
    case 6:  return TRUE;
    case 7:  if (hyp) fasinh(x,x);
             else     fasin(x,x);
             if (degrees) fdiv(x,radeg,x);
             newx=TRUE;
             break;
    case 8:  if (hyp) facosh(x,x);
             else     facos(x,x);
             if (degrees) fdiv(x,radeg,x);
             newx=TRUE;
             break;
    case 9:  if (hyp) fatanh(x,x);
             else     fatan(x,x);
             if (degrees) fdiv(x,radeg,x);
             newx=TRUE;
             break;
    case 10: flog(x,x);
             if (lgbase==2)  fdiv(x,loge2,x);
             if (lgbase==10) fdiv(x,loge10,x);
             newx=TRUE;
             break;
    case 11: newx=TRUE;
             k=3;
             forever
             {
                 aprint(INVER,2+stptr[k],2,settings[k][option[k]]);
                 curser(2+stptr[k],2);
                 c=arrow(gethit());
                 if (c==1)
                 {
                     if (option[k]==nops[k]) option[k]=0;
                     else option[k]+=1;
                     continue;
                 }
                 aprint(STATCOL,2+stptr[k],2,settings[k][option[k]]);
                 if (c==0 || c==2) break;
                 if (c==4 && k>0) k--;
                 if (c==3 && k<3) k++;
             }
             setopts();
             break;
    case 12: chekit(7);
             break;
    case 13: result=FALSE;
             if (ipt==0) break;
             ipt--;
             mybuff[ipt]='\0';
             if (ipt==0) clr();
             just(mybuff);
             cinstr(x,mybuff);
             newx=TRUE;
             break;
    case 14: if (!next('7')) putchar(BELL);
             break;
    case 15: if (!next('8')) putchar(BELL);
             break;
    case 16: if (!next('9')) putchar(BELL);
             break;
    case 17: chekit(6);
             break;
    case 18: chekit(5);
             break;
    case 19: chekit(4);
             break;
    case 20: copy(m,x);
             newx=TRUE;
             break;
    case 21: if (!next('4')) putchar(BELL);
             break;
    case 22: if (!next('5')) putchar(BELL);
             break;
    case 23: if (!next('6')) putchar(BELL);
             break;
    case 24: fmul(x,x,x);
             newx=TRUE;
             break;
    case 25: froot(x,2,x);
             newx=TRUE;
             break;
    case 26: chekit(3);
             break;
    case 27: brkt=0;
             chekit(0);
             flag=OFF;
             fadd(m,x,m);
             newx=TRUE;
             break;
    case 28: if (!next('1')) putchar(BELL);
             break;
    case 29: if (!next('2')) putchar(BELL);
             break;
    case 30: if (!next('3')) putchar(BELL);
             break;
    case 31: frecip(x,x);
             newx=TRUE;
             break;
    case 32: fpi(x);
             newx=TRUE;
             break;
    case 33: chekit(2);
             break;
    case 34: negify(x,x);
             newx=TRUE;
             break;
    case 35: if (!next('0')) putchar(BELL);
             break;
    case 36: if (!next('/')) putchar(BELL);
             break;
    case 37: if (!next('.')) putchar(BELL);
             break;
    case 38: if (ipt>0)
             {
                 putchar(BELL);
                 result=FALSE;
             }
             else
             {
                 zero(x);
                 brkt+=1;
                 newx=TRUE;
             }
             break;
    case 39: if (brkt>0)
             {
                 chekit(0);
                 brkt-=1;
             }
             else
             {
                 putchar(BELL);
                 result=FALSE;
             }
             break;
    case 40: chekit(1);
             break;
    case 41: brkt=0;
             equals(0);
             flag=OFF;
             break;
    }
    return FALSE;
}
Ejemplo n.º 4
0
int xgcd(_MIPD_ big x,big y,big xd,big yd,big z)
{ /* greatest common divisor by Euclids method  *
   * extended to also calculate xd and yd where *
   *      z = x.xd + y.yd = gcd(x,y)            *
   * if xd, yd not distinct, only xd calculated *
   * z only returned if distinct from xd and yd *
   * xd will always be positive, yd negative    */

    int s,n,iter;
    mr_small r,a,b,c,d;
    mr_small q,m,sr;
#ifdef MR_FP
    mr_small dres;
#endif

#ifdef mr_dltype
    union doubleword uu,vv;
    mr_large u,v,lr;
#else
    mr_small u,v,lr;
#endif

    BOOL last,dplus=TRUE;
    big t;
#ifdef MR_OS_THREADS
    miracl *mr_mip=get_mip();
#endif

    if (mr_mip->ERNUM) return 0;

    MR_IN(30)

#ifdef MR_COUNT_OPS
    fpx++; 
#endif
  
    copy(x,mr_mip->w1);
    copy(y,mr_mip->w2);
    s=exsign(mr_mip->w1);
    insign(PLUS,mr_mip->w1);
    insign(PLUS,mr_mip->w2);
    convert(_MIPP_ 1,mr_mip->w3);
    zero(mr_mip->w4);
    last=FALSE;
    a=b=c=d=0;
    iter=0;

    while (size(mr_mip->w2)!=0)
    {
        if (b==0)
        { /* update mr_mip->w1 and mr_mip->w2 */

            divide(_MIPP_ mr_mip->w1,mr_mip->w2,mr_mip->w5);
            t=mr_mip->w1,mr_mip->w1=mr_mip->w2,mr_mip->w2=t;    /* swap(mr_mip->w1,mr_mip->w2) */
            multiply(_MIPP_ mr_mip->w4,mr_mip->w5,mr_mip->w0);
            add(_MIPP_ mr_mip->w3,mr_mip->w0,mr_mip->w3);
            t=mr_mip->w3,mr_mip->w3=mr_mip->w4,mr_mip->w4=t;    /* swap(xd,yd) */
            iter++;

        }
        else
        {

 /* printf("a= %I64u b= %I64u c= %I64u  d= %I64u \n",a,b,c,d);   */

            mr_pmul(_MIPP_ mr_mip->w1,c,mr_mip->w5);   /* c*w1 */
            mr_pmul(_MIPP_ mr_mip->w1,a,mr_mip->w1);   /* a*w1 */
            mr_pmul(_MIPP_ mr_mip->w2,b,mr_mip->w0);   /* b*w2 */
            mr_pmul(_MIPP_ mr_mip->w2,d,mr_mip->w2);   /* d*w2 */

            if (!dplus)
            {
                mr_psub(_MIPP_ mr_mip->w0,mr_mip->w1,mr_mip->w1); /* b*w2-a*w1 */
                mr_psub(_MIPP_ mr_mip->w5,mr_mip->w2,mr_mip->w2); /* c*w1-d*w2 */
            }
            else
            {
                mr_psub(_MIPP_ mr_mip->w1,mr_mip->w0,mr_mip->w1); /* a*w1-b*w2 */
                mr_psub(_MIPP_ mr_mip->w2,mr_mip->w5,mr_mip->w2); /* d*w2-c*w1 */
            }
            mr_pmul(_MIPP_ mr_mip->w3,c,mr_mip->w5);
            mr_pmul(_MIPP_ mr_mip->w3,a,mr_mip->w3);
            mr_pmul(_MIPP_ mr_mip->w4,b,mr_mip->w0);
            mr_pmul(_MIPP_ mr_mip->w4,d,mr_mip->w4);
    
            if (a==0) copy(mr_mip->w0,mr_mip->w3);
            else      mr_padd(_MIPP_ mr_mip->w3,mr_mip->w0,mr_mip->w3);
            mr_padd(_MIPP_ mr_mip->w4,mr_mip->w5,mr_mip->w4);
        }
        if (mr_mip->ERNUM || size(mr_mip->w2)==0) break;


        n=(int)mr_mip->w1->len;
        if (n==1)
        {
            last=TRUE;
            u=mr_mip->w1->w[0];
            v=mr_mip->w2->w[0];
        }
        else
        {
            m=mr_mip->w1->w[n-1]+1;
#ifndef MR_SIMPLE_BASE
            if (mr_mip->base==0)
            {
#endif
#ifndef MR_NOFULLWIDTH
#ifdef mr_dltype
 /* use double length type if available */
                if (n>2 && m!=0)
                { /* squeeze out as much significance as possible */
                    uu.h[MR_TOP]=muldvm(mr_mip->w1->w[n-1],mr_mip->w1->w[n-2],m,&sr);
                    uu.h[MR_BOT]=muldvm(sr,mr_mip->w1->w[n-3],m,&sr);
                    vv.h[MR_TOP]=muldvm(mr_mip->w2->w[n-1],mr_mip->w2->w[n-2],m,&sr);
                    vv.h[MR_BOT]=muldvm(sr,mr_mip->w2->w[n-3],m,&sr);
                }
                else
                {
                    uu.h[MR_TOP]=mr_mip->w1->w[n-1];
                    uu.h[MR_BOT]=mr_mip->w1->w[n-2];
                    vv.h[MR_TOP]=mr_mip->w2->w[n-1];
                    vv.h[MR_BOT]=mr_mip->w2->w[n-2];
                    if (n==2) last=TRUE;
                }

                u=uu.d;
                v=vv.d;
#else
                if (m==0)
                {
                    u=mr_mip->w1->w[n-1];
                    v=mr_mip->w2->w[n-1];   
                }
                else
                {
                    u=muldvm(mr_mip->w1->w[n-1],mr_mip->w1->w[n-2],m,&sr);
                    v=muldvm(mr_mip->w2->w[n-1],mr_mip->w2->w[n-2],m,&sr);
                }
#endif
#endif
#ifndef MR_SIMPLE_BASE
            }
            else
            {
#ifdef mr_dltype
                if (n>2)
                { /* squeeze out as much significance as possible */
                    u=muldiv(mr_mip->w1->w[n-1],mr_mip->base,mr_mip->w1->w[n-2],m,&sr);
                    u=u*mr_mip->base+muldiv(sr,mr_mip->base,mr_mip->w1->w[n-3],m,&sr);
                    v=muldiv(mr_mip->w2->w[n-1],mr_mip->base,mr_mip->w2->w[n-2],m,&sr);
                    v=v*mr_mip->base+muldiv(sr,mr_mip->base,mr_mip->w2->w[n-3],m,&sr);
                }
                else
                {
                    u=(mr_large)mr_mip->base*mr_mip->w1->w[n-1]+mr_mip->w1->w[n-2];
                    v=(mr_large)mr_mip->base*mr_mip->w2->w[n-1]+mr_mip->w2->w[n-2];
                    last=TRUE;
                }
#else
                u=muldiv(mr_mip->w1->w[n-1],mr_mip->base,mr_mip->w1->w[n-2],m,&sr);
                v=muldiv(mr_mip->w2->w[n-1],mr_mip->base,mr_mip->w2->w[n-2],m,&sr);
#endif
            }
#endif
        }

        dplus=TRUE;
        a=1; b=0; c=0; d=1;

        forever
        { /* work only with most significant piece */
            if (last)
            {
                if (v==0) break;
                q=qdiv(u,v);
                if (q==0) break;
            }
            else
            {
                if (dplus)
                { 
                    if ((mr_small)(v-c)==0 || (mr_small)(v+d)==0) break;

                    q=qdiv(u+a,v-c);

                    if (q==0) break;

                    if (q!=qdiv(u-b,v+d)) break;
                }
                else 
                {
                    if ((mr_small)(v+c)==0 || (mr_small)(v-d)==0) break;
                    q=qdiv(u-a,v+c);
                    if (q==0) break;
                    if (q!=qdiv(u+b,v-d)) break;
                }
            }

            if (q==1)
            {
                if ((mr_small)(b+d) >= MAXBASE) break; 
                r=a+c;  a=c; c=r;
                r=b+d;  b=d; d=r;
                lr=u-v; u=v; v=lr;      
            }
            else
            { 
                if (q>=MR_DIV(MAXBASE-b,d)) break;
                r=a+q*c;  a=c; c=r;
                r=b+q*d;  b=d; d=r;
                lr=u-q*v; u=v; v=lr;
            }
            iter++;
            dplus=!dplus;
        }
        iter%=2;

    }

    if (s==MINUS) iter++;
    if (iter%2==1) subtract(_MIPP_ y,mr_mip->w3,mr_mip->w3);

    if (xd!=yd)
    {
        negify(x,mr_mip->w2);
        mad(_MIPP_ mr_mip->w2,mr_mip->w3,mr_mip->w1,y,mr_mip->w4,mr_mip->w4);
        copy(mr_mip->w4,yd);
    }
    copy(mr_mip->w3,xd);
    if (z!=xd && z!=yd) copy(mr_mip->w1,z);

    MR_OUT
    return (size(mr_mip->w1));
}
Ejemplo n.º 5
0
Big operator-(int i, const Big& b)
{Big mib;decr(b.fn, i, mib.fn);negify(mib.fn,mib.fn);return mib;}
Ejemplo n.º 6
0
Big operator-(const Big& b)
{Big nb; negify(b.fn,nb.fn); return nb;}
Ejemplo n.º 7
0
void Big::negate() const
         { negify(fn,fn); }
Ejemplo n.º 8
0
int main()
{  /*  factoring program using Williams (p+1) method */
    int k,phase,m,nt,iv,pos,btch;
    long i,p,pa,interval;
    big b,q,n,fp,fvw,fd,fn,t;
    static big fu[1+MULT/2];
    static BOOL cp[1+MULT/2];
    mip=mirsys(30,0);
    b=mirvar(0);
    q=mirvar(0);
    n=mirvar(0);
    t=mirvar(0);
    fp=mirvar(0);
    fvw=mirvar(0);
    fd=mirvar(0);
    fn=mirvar(0);
    gprime(LIMIT1);
    for (m=1;m<=MULT/2;m+=2)
        if (igcd(MULT,m)==1)
        {
            fu[m]=mirvar(0);
            cp[m]=TRUE;
        }
        else cp[m]=FALSE;
    printf("input number to be factored\n");
    cinnum(n,stdin);
    if (isprime(n))
    {
        printf("this number is prime!\n");
        return 0;
    }
    for (nt=0,k=3;k<10;k++)
    { /* try more than once for p+1 condition (may be p-1) */
        convert(k,b);              /* try b=3,4,5..        */
        convert((k*k-4),t);
        if (egcd(t,n,t)!=1) continue; /* check (b*b-4,n)!=0 */
        nt++;
        phase=1;
        p=0;
        btch=50;
        i=0;
        printf("phase 1 - trying all primes less than %d\n",LIMIT1);
        printf("prime= %8ld",p);
        forever
        { /* main loop */
            if (phase==1)
            { /* looking for all factors of p+1 < LIMIT1 */
                p=mip->PRIMES[i];
                if (mip->PRIMES[i+1]==0)
                { /* now change gear */
                    phase=2;
                    printf("\nphase 2 - trying last prime less than %ld\n"
                           ,LIMIT2);
                    printf("prime= %8ld",p);
                    copy(b,fu[1]);
                    copy(b,fp);
                    mad(b,b,b,n,n,fd);
                    decr(fd,2,fd);     
                    negify(b,t);
                    mad(fd,b,t,n,n,fn);
                    for (m=5;m<=MULT/2;m+=2)
                    { /* store fu[m] = Vm(b) */
                        negify(fp,t);
                        mad(fn,fd,t,n,n,t);
                        copy(fn,fp);
                        copy(t,fn);
                        if (!cp[m]) continue;
                        copy(t,fu[m]);
                    }
                    convert(MULT,t);    
                    lucas(b,t,n,fp,fd);
                    iv=(int)(p/MULT);
                    if (p%MULT>MULT/2) iv++;
                    interval=(long)iv*MULT;
                    p=interval+1;
                    convert(iv,t);
                    lucas(fd,t,n,fp,fvw);
                    negify(fp,fp);
                    subtract(fvw,fu[p%MULT],q);
                    marks(interval);
                    btch*=100;
                    i++;
                    continue;
                }
                pa=p;
                while ((LIMIT1/p) > pa) pa*=p;
                convert((int)pa,t);   
                lucas(b,t,n,fp,q);
                copy(q,b);
                decr(q,2,q);
            }
            else
            { /* phase 2 - looking for last large prime factor of (p+1) */
                p+=2;
                pos=(int)(p%MULT);
                if (pos>MULT/2)
                { /* increment giant step */
                    iv++;
                    interval=(long)iv*MULT;
                    p=interval+1;
                    marks(interval);
                    pos=1;
                    copy(fvw,t);
                    mad(fvw,fd,fp,n,n,fvw);
                    negify(t,fp);
                }
                if (!cp[pos]) continue;

        /* if neither interval+/-pos is prime, don't bother */
                if (!plus[pos] && !minus[pos]) continue;
                subtract(fvw,fu[pos],t);
                mad(q,t,t,n,n,q);  /* batching gcds */
            }
            if (i++%btch==0)
            { /* try for a solution */
                printf("\b\b\b\b\b\b\b\b%8ld",p);
                fflush(stdout);
                egcd(q,n,t);
                if (size(t)==1)
                {
                    if (p>LIMIT2) break;
                    else continue;
                }
                if (compare(t,n)==0)
                {
                    printf("\ndegenerate case");
                    break;
                }
                printf("\nfactors are\n");
                if (isprime(t)) printf("prime factor     ");
                else          printf("composite factor ");
                cotnum(t,stdout);
                divide(n,t,n);
                if (isprime(n)) printf("prime factor     ");
                else          printf("composite factor ");
                cotnum(n,stdout);
                return 0;
            }
        } 
        if (nt>=NTRYS) break;
        printf("\ntrying again\n");
    }
    printf("\nfailed to factor\n");
    return 0;
}
Ejemplo n.º 9
0
void build(_MIPD_ flash x,int (*gen)(_MIPT_ big,int))
{ /* Build x from its regular c.f. *
   * generated by gen()            */
    mr_small ex1,ex2,ex,st,sr;
    int a,b,c,d,rm,q,n,prc,lw2,lw4,lz;
    BOOL finoff,last;
    big t;
#ifdef MR_OS_THREADS
    miracl *mr_mip=get_mip();
#endif
    if (mr_mip->ERNUM) return;

    MR_IN(48)

    zero(mr_mip->w1);
    convert(_MIPP_ 1,mr_mip->w2);
    convert(_MIPP_ 1,mr_mip->w3);
    zero(mr_mip->w4);
    finoff=FALSE;
    last=FALSE;
    n=0;
    q=(*gen)(_MIPP_ x,n);   /* Note - first quotient may be zero */
    ex=mr_mip->base-1;
    if (mr_mip->nib==mr_mip->workprec) prc=mr_mip->nib;
    else prc=mr_mip->workprec+1;
    while (!mr_mip->ERNUM && q>=0)
    {
        if (q==MR_TOOBIG || n==0 || finoff)
        {
            if (q!=MR_TOOBIG) convert(_MIPP_ q,x);
            else last=FALSE;
            mr_mip->check=OFF;
            multiply(_MIPP_ mr_mip->w2,x,mr_mip->w0);
            subtract(_MIPP_ mr_mip->w1,mr_mip->w0,mr_mip->w7);
            mr_mip->check=ON;
            if ((int)(mr_mip->w7->len&MR_OBITS)>mr_mip->nib) break;
            copy(mr_mip->w7,mr_mip->w1);
            t=mr_mip->w1,mr_mip->w1=mr_mip->w2,mr_mip->w2=t;   /* swap(w1,w2) */
            mr_mip->check=OFF;
            multiply(_MIPP_ mr_mip->w4,x,mr_mip->w0);
            subtract(_MIPP_ mr_mip->w3,mr_mip->w0,mr_mip->w7);
            mr_mip->check=ON;
            if ((int)(mr_mip->w7->len&MR_OBITS)>mr_mip->nib)
            { /* oops! */
                fpack(_MIPP_ mr_mip->w1,mr_mip->w4,x);
                negify(x,x);
                mr_mip->EXACT=FALSE;
                MR_OUT
                return;
            }
            copy(mr_mip->w7,mr_mip->w3);
            t=mr_mip->w3,mr_mip->w3=mr_mip->w4,mr_mip->w4=t;   /* swap(w3,w4) */
            n++;
        }
        lw2=(int)(mr_mip->w2->len&MR_OBITS);
        lw4=(int)(mr_mip->w4->len&MR_OBITS);
        lz=lw2+lw4;
        if (lz > prc) break;  /* too big - exit */
        if (last)
        {
            if (finoff) break;
            finoff=TRUE;
            q=(*gen)(_MIPP_ x,n);
            continue;
        }
        if (lz>=prc-1)
        { /* nearly finished - so be careful not to overshoot */
            if (mr_mip->base==0)
            {
#ifndef MR_NOFULLWIDTH
                st=mr_mip->w2->w[lw2-1]+1;
                if (st==0) ex1=1;
                else ex1=muldvm((mr_small)1,(mr_small)0,st,&sr);
                st=mr_mip->w4->w[lw4-1]+1;
                if (st==0) ex2=1;
                else ex2=muldvm((mr_small)1,(mr_small)0,st,&sr);
#endif
            }
            else
            {
                ex1=mr_mip->base/(mr_mip->w2->w[lw2-1]+1);
                ex2=mr_mip->base/(mr_mip->w4->w[lw4-1]+1);
            }
            if (ex2>ex1) ex=ex1,ex1=ex2,ex2=ex;
            if (lz==prc) ex=ex2;
            else         ex=ex1;
            last=TRUE;
        }
        a=1;
        b=0;
        c=0;
        d=1;
        forever
        {
            q=(*gen)(_MIPP_ x,n);          
            if (q<0 || q>=MR_TOOBIG/mr_abs(d))
            { /* there could be more.... *** V3.21 mod *** */
                last=FALSE;
                break;
            }
            rm=b-q*d;
            b=d;
            d=rm;
            rm=a-q*c;
            a=c;
            c=rm;
            n++;
            if ((mr_small)(mr_abs(c-d))>ex) break;
        }
        premult(_MIPP_ mr_mip->w1,c,mr_mip->w7);
        premult(_MIPP_ mr_mip->w1,a,mr_mip->w1);
        premult(_MIPP_ mr_mip->w2,b,mr_mip->w0);
        premult(_MIPP_ mr_mip->w2,d,mr_mip->w2);
        add(_MIPP_ mr_mip->w1,mr_mip->w0,mr_mip->w1);
        add(_MIPP_ mr_mip->w2,mr_mip->w7,mr_mip->w2);
        premult(_MIPP_ mr_mip->w3,c,mr_mip->w7);
        premult(_MIPP_ mr_mip->w3,a,mr_mip->w3);
        premult(_MIPP_ mr_mip->w4,b,mr_mip->w0);
        premult(_MIPP_ mr_mip->w4,d,mr_mip->w4);
        add(_MIPP_ mr_mip->w3,mr_mip->w0,mr_mip->w3);
        add(_MIPP_ mr_mip->w4,mr_mip->w7,mr_mip->w4);
    }