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Annotation of 43BSD/usr.lib/liboldnm/pow.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1980 Regents of the University of California.
        !             3:  * All rights reserved.  The Berkeley software License Agreement
        !             4:  * specifies the terms and conditions for redistribution.
        !             5:  */
        !             6: 
        !             7: #ifndef lint
        !             8: static char sccsid[] = "@(#)pow.c      5.1 (Berkeley) 5/8/85";
        !             9: #endif not lint
        !            10: 
        !            11: /*
        !            12:        computes a^b.
        !            13:        uses log and exp
        !            14: */
        !            15: 
        !            16: #include       <errno.h>
        !            17: int errno;
        !            18: double log(), exp();
        !            19: 
        !            20: double
        !            21: pow(arg1,arg2)
        !            22: double arg1, arg2;
        !            23: {
        !            24:        double temp;
        !            25:        long l;
        !            26: 
        !            27:        asm("   bispsw  $0xe0");
        !            28:        if(arg1 <= 0.) {
        !            29:                if(arg1 == 0.) {
        !            30:                        if(arg2 <= 0.)
        !            31:                                goto domain;
        !            32:                        return(0.);
        !            33:                }
        !            34:                l = arg2;
        !            35:                if(l != arg2)
        !            36:                        goto domain;
        !            37:                temp = exp(arg2 * log(-arg1));
        !            38:                if(l & 1)
        !            39:                        temp = -temp;
        !            40:                return(temp);
        !            41:        }
        !            42:        return(exp(arg2 * log(arg1)));
        !            43: 
        !            44: domain:
        !            45:        errno = EDOM;
        !            46:        return(0.);
        !            47: }

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