1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
28 /* All Rights Reserved */
29
30 #pragma ident "%Z%%M% %I% %E% SMI"
31
32 /* factor COMPILE: cc -O factor.c -s -i -lm -o factor */
33 /*
34 * works up to 14 digit numbers
35 * running time is proportional to sqrt(n)
36 * accepts arguments either as input or on command line
37 * 0 input terminates processing
38 */
39
40 double modf(), sqrt();
41 double nn, vv;
42 double huge = 1.0e14;
43 double sq[] = {
44 10, 2, 4, 2, 4, 6, 2, 6,
45 4, 2, 4, 6, 6, 2, 6, 4,
46 2, 6, 4, 6, 8, 4, 2, 4,
47 2, 4, 8, 6, 4, 6, 2, 4,
48 6, 2, 6, 6, 4, 2, 4, 6,
49 2, 6, 4, 2, 4, 2,10, 2,
50 };
51
52 void try(double);
53
54 int
main(int argc,char * argv[])55 main(int argc, char *argv[])
56 {
57 int test = 1;
58 int ret;
59 int j;
60 double junk, temp;
61 double fr;
62 double ii;
63
64 if(argc > 2){
65 printf("Usage: factor number\n");
66 exit(1);
67 }
68 if(argc == 2){
69 ret = sscanf(argv[1], "%lf", &nn);
70 test = 0;
71 printf("%.0f\n", nn);
72 goto start;
73 }
74 while(test == 1){
75 ret = scanf("%lf", &nn);
76 start:
77 if((ret<1) || (nn == 0.0)){
78 exit(0);
79 }
80 if((nn<0.0) || (nn>huge)){
81 printf("Ouch!\n");
82 continue;
83 }
84 fr = modf(nn, &junk);
85 if(fr != 0.0){
86 printf("Not an integer!\n");
87 continue;
88 }
89 vv = 1. + sqrt(nn);
90 try(2.0);
91 try(3.0);
92 try(5.0);
93 try(7.0);
94 ii = 1.0;
95 while(ii <= vv){
96 for(j=0; j<48; j++){
97 ii += sq[j];
98 retry:
99 modf(nn/ii, &temp);
100 if(nn == temp*ii){
101 printf(" %.0f\n", ii);
102 nn = nn/ii;
103 vv = 1 + sqrt(nn);
104 goto retry;
105 }
106 }
107 }
108 if(nn > 1.0){
109 printf(" %.0f\n", nn);
110 }
111 printf("\n");
112 }
113 return (0);
114 }
115
116 void
try(double arg)117 try(double arg)
118 {
119 double temp;
120 retry:
121 modf(nn/arg, &temp);
122 if(nn == temp*arg){
123 printf(" %.0f\n", arg);
124 nn = nn/arg;
125 vv = 1 + sqrt(nn);
126 goto retry;
127 }
128 }
129