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Annotation of coherent/d/usr/lib/libmp/rpow.c, revision 1.1.1.1

1.1       root        1: #include "mprec.h"
                      2: 
                      3: 
                      4: /*
                      5:  *     Rpow sets the mint pointed to by "c" to the mint pointed to by "a"
                      6:  *     raised to the mint pointed to by "b" power.  If "b" is negative then
                      7:  *     mperr is called with the appropriate error message.
                      8:  *     Note that no assumption is made as to the distinctness of "a", "b" and
                      9:  *     "c".
                     10:  */
                     11: 
                     12: void
                     13: rpow(a, b, c)
                     14: register mint *a, *b, *c;
                     15: {
                     16:        mint    al, bl;
                     17:        int rem;
                     18: 
                     19:        if (!ispos(b))
                     20:                mperr("negative power");
                     21: 
                     22:        /* make local copies of a and b */
                     23:        minit(&al);
                     24:        mcopy(a, &al);
                     25:        minit(&bl);
                     26:        mcopy(b, &bl);
                     27: 
                     28:        /* form actual power */
                     29:        sdiv(&bl, 2, &bl, &rem);
                     30:        if (rem != 0)
                     31:                mcopy(&al, c);
                     32:        else
                     33:                mcopy(mone, c);
                     34:        while (!zerop(&bl)) {
                     35:                mult(&al, &al, &al);
                     36:                sdiv(&bl, 2, &bl, &rem);
                     37:                if (rem != 0)
                     38:                        mult(c, &al, c);
                     39:        }
                     40: 
                     41:        /* clean up garbage */
                     42:        mpfree(al.val);
                     43:        mpfree(bl.val);
                     44: }

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