projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| a0dba064 SL |
1 | /* @(#)msqrt.c 4.1 %G% */ |
| 2 | ||
| 3 | #include <mp.h> | |
| 4 | msqrt(a,b,r) MINT *a,*b,*r; | |
| 5 | { MINT x,junk,y; | |
| 6 | int j; | |
| 7 | x.len=junk.len=y.len=0; | |
| 8 | if(a->len<0) fatal("msqrt: neg arg"); | |
| 9 | if(a->len==0) | |
| 10 | { b->len=0; | |
| 11 | r->len=0; | |
| 12 | return(0); | |
| 13 | } | |
| 14 | if(a->len%2==1) x.len=(1+a->len)/2; | |
| 15 | else x.len=1+a->len/2; | |
| 16 | x.val=xalloc(x.len,"msqrt"); | |
| 17 | for(j=0;j<x.len;x.val[j++]=0); | |
| 18 | if(a->len%2==1) x.val[x.len-1]=0400; | |
| 19 | else x.val[x.len-1]=1; | |
| 20 | xfree(b); | |
| 21 | xfree(r); | |
| 22 | loop: | |
| 23 | mdiv(a,&x,&y,&junk); | |
| 24 | xfree(&junk); | |
| 25 | madd(&x,&y,&y); | |
| 26 | sdiv(&y,2,&y,(short *)&j); | |
| 27 | if(mcmp(&x,&y)>0) | |
| 28 | { xfree(&x); | |
| 29 | move(&y,&x); | |
| 30 | xfree(&y); | |
| 31 | goto loop; | |
| 32 | } | |
| 33 | xfree(&y); | |
| 34 | move(&x,b); | |
| 35 | mult(&x,&x,&x); | |
| 36 | msub(a,&x,r); | |
| 37 | xfree(&x); | |
| 38 | return(r->len); | |
| 39 | } |