paper.ps

c programming pearls answer

(factor of 5-10 difference in runtime, with a total range that exceeds three orders of magnitude.)15 3754 1 720 5664 t
10 B f
(Function Calls)1 626 1 720 5904 t
10 R f
( Computing)1 516( evaluates Ackermann's function.)3 1386(The next program)2 743 3 970 6060 t
10 I f
(ack)3655 6060 w
10 R f
(\( 3 ,)2 124 1 3801 6060 t
10 I f
(k)3933 6060 w
10 R f
(\))3985 6060 w
10 S f
(=)4075 6060 w
10 R f
(2)4179 6060 w
7 R f
(\()4234 6020 w
7 I f
(k)4262 6020 w
7 S f
(+)4309 6020 w
7 R f
(3 \))1 63 1 4359 6020 t
10 S f
(-)4446 6060 w
10 R f
(3 requires at)2 523 1 4517 6060 t
(least 4)1 268 1 720 6180 t
7 R f
(\()993 6140 w
7 I f
(k)1021 6140 w
7 S f
(+)1068 6140 w
7 R f
(1 \))1 63 1 1118 6140 t
10 R f
(function calls, and reaches a recursive depth of 2)8 2027 1 1224 6180 t
7 R f
(\()3256 6140 w
7 I f
(k)3284 6140 w
7 S f
(+)3331 6140 w
7 R f
(3 \))1 63 1 3381 6140 t
10 S f
(-)3468 6180 w
10 R f
( function call)2 545(1, so this test gives the)5 956 2 3539 6180 t
( code looks similar in most languages; here it is in C and Java:)13 2496( The)1 205(mechanism a thorough workout.)3 1293 3 720 6300 t
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7 pagesetup
10 R f
(- 7 -)2 166 1 2797 480 t
9 CW f
(int ack\(int m, int n\) {)5 1242 1 1008 830 t
(if \(m == 0\))3 594 1 1440 940 t
(return n+1;)1 594 1 1872 1050 t
(else if \(n == 0\))4 864 1 1440 1160 t
(return ack\(m-1, 1\);)2 1026 1 1872 1270 t
(else)1440 1380 w
(return ack\(m-1, ack\(m, n-1\)\);)3 1566 1 1872 1490 t
(})1008 1600 w
10 R f
(and in Scheme:)2 616 1 720 1816 t
9 CW f
(\(define \(ack m n\))3 918 1 1008 1986 t
(\(cond \(\(= m 0\) \(+ n 1\)\))6 1242 1 1332 2096 t
(\(\(= n 0\) \(ack \(- m 1\) 1\)\))7 1350 1 1656 2206 t
(\(else \(ack \(- m 1\) \(ack m \(- n 1\)\)\)\)\)\))9 2052 1 1656 2316 t
10 R f
2280 4122 1200 4122 Dl
1200 2682 1200 4122 Dl
1334 4194 1334 4122 Dl
(5)1309 4304 w
1604 4194 1604 4122 Dl
(6)1579 4304 w
1874 4194 1874 4122 Dl
(7)1849 4304 w
2144 4194 2144 4122 Dl
(8)2119 4304 w
(Irix)1668 2617 w
10 CW f
(k)1710 4442 w
10 R f
(seconds)729 3422 w
1164 3815 1200 3815 Dl
(0.1)1014 3835 w
1164 3509 1200 3509 Dl
(1)1089 3529 w
1164 3202 1200 3202 Dl
(10)1039 3222 w
1164 2896 1200 2896 Dl
[phone] w
7 S1 f
()1321 3995 w
1321 3995 m
27 build_ob
1348 3995 m
()1591 3849 w
1591 3849 m
27 build_ob
1618 3849 m
7 R f
(.)1324 3978 w
(.)1355 3962 w
(.)1385 3946 w
(.)1414 3929 w
(.)1445 3914 w
(.)1475 3897 w
(.)1504 3881 w
(.)1535 3865 w
(.)1565 3848 w
(.)1594 3832 w
7 S1 f
()1861 3661 w
1861 3661 m
27 build_ob
1888 3661 m
7 R f
(.)1594 3832 w
(.)1625 3811 w
(.)1655 3790 w
(.)1684 3770 w
(.)1715 3749 w
(.)1745 3728 w
(.)1774 3707 w
(.)1805 3686 w
(.)1835 3665 w
(.)1864 3644 w
7 S1 f
()2131 3466 w
2131 3466 m
27 build_ob
2158 3466 m
7 R f
(.)1864 3644 w
(.)1895 3622 w
(.)1925 3600 w
(.)1954 3579 w
(.)1985 3557 w
(.)2015 3536 w
(.)2044 3514 w
(.)2075 3492 w
(.)2105 3471 w
(.)2134 3449 w
8 R f
(C)2184 3466 w
7 S1 f
()1321 3443 w
1321 3443 m
27 build_ob
1348 3443 m
()1591 3257 w
1591 3257 m
27 build_ob
1618 3257 m
7 R f
(.)1324 3426 w
(.)1355 3405 w
(.)1385 3385 w
(.)1414 3364 w
(.)1445 3343 w
(.)1475 3322 w
(.)1504 3302 w
(.)1535 3281 w
(.)1565 3261 w
(.)1594 3240 w
7 S1 f
()1861 3067 w
1861 3067 m
27 build_ob
1888 3067 m
7 R f
(.)1594 3240 w
(.)1625 3219 w
(.)1655 3198 w
(.)1684 3177 w
(.)1715 3155 w
(.)1745 3135 w
(.)1774 3114 w
(.)1805 3093 w
(.)1835 3071 w
(.)1864 3050 w
7 S1 f
()2131 2873 w
2131 2873 m
27 build_ob
2158 2873 m
7 R f
(.)1864 3050 w
(.)1895 3029 w
(.)1925 3007 w
(.)1954 2985 w
(.)1985 2964 w
(.)2015 2942 w
(.)2044 2921 w
(.)2075 2899 w
(.)2105 2877 w
(.)2134 2856 w
8 R f
(Awk)2184 2873 w
7 S1 f
()1321 3295 w
1321 3295 m
27 build_ob
1348 3295 m
()1591 3105 w
1591 3105 m
27 build_ob
1618 3105 m
7 R f
(.)1324 3278 w
(.)1355 3257 w
(.)1385 3235 w
(.)1414 3214 w
(.)1445 3194 w
(.)1475 3173 w
(.)1504 3152 w
(.)1535 3131 w
(.)1565 3109 w
(.)1594 3088 w
7 S1 f
()1861 2916 w
1861 2916 m
27 build_ob
1888 2916 m
7 R f
(.)1594 3088 w
(.)1625 3068 w
(.)1655 3047 w
(.)1684 3025 w
(.)1715 3004 w
(.)1745 2983 w
(.)1774 2962 w
(.)1805 2941 w
(.)1835 2920 w
(.)1864 2899 w
8 R f
(Perl)1914 2916 w
7 S1 f
()1321 3188 w
1321 3188 m
27 build_ob
1348 3188 m
()1591 2997 w
1591 2997 m
27 build_ob
1618 2997 m
7 R f
(.)1324 3171 w
(.)1355 3149 w
(.)1385 3128 w
(.)1414 3107 w
(.)1445 3086 w
(.)1475 3065 w
(.)1504 3044 w
(.)1535 3023 w
(.)1565 3002 w
(.)1594 2980 w
7 S1 f
()1861 2799 w
1861 2799 m
27 build_ob
1888 2799 m
7 R f
(.)1594 2980 w
(.)1625 2959 w
(.)1655 2937 w
(.)1684 2914 w
(.)1715 2893 w
(.)1745 2870 w
(.)1774 2849 w
(.)1805 2826 w
(.)1835 2804 w
(.)1864 2782 w
8 R f
(Tcl)1914 2799 w
7 S1 f
()1321 3613 w
1321 3613 m
27 build_ob
1348 3613 m
()1591 3406 w
1591 3406 m
27 build_ob
1618 3406 m
7 R f
(.)1324 3596 w
(.)1355 3573 w
(.)1385 3550 w
(.)1414 3528 w
(.)1445 3505 w
(.)1475 3482 w
(.)1504 3459 w
(.)1535 3435 w
(.)1565 3412 w
(.)1594 3389 w
7 S1 f
()1861 3210 w
1861 3210 m
27 build_ob
1888 3210 m
7 R f
(.)1594 3389 w
(.)1625 3368 w
(.)1655 3346 w
(.)1684 3324 w
(.)1715 3302 w
(.)1745 3280 w
(.)1774 3258 w
(.)1805 3236 w
(.)1835 3214 w
(.)1864 3193 w
7 S1 f
()2131 3016 w
2131 3016 m
27 build_ob
2158 3016 m
7 R f
(.)1864 3193 w
(.)1895 3171 w
(.)1925 3150 w
(.)1954 3128 w
(.)1985 3106 w
(.)2015 3085 w
(.)2044 3064 w
(.)2075 3042 w
(.)2105 3021 w
(.)2134 2999 w
8 R f
(Limbo)2184 3016 w
7 S1 f
()1321 3401 w
1321 3401 m
27 build_ob
1348 3401 m
()1591 3216 w
1591 3216 m
27 build_ob
1618 3216 m
7 R f
(.)1324 3384 w
(.)1355 3363 w
(.)1385 3343 w
(.)1414 3322 w
(.)1445 3302 w
(.)1475 3281 w
(.)1504 3261 w
(.)1535 3240 w
(.)1565 3219 w
(.)1594 3199 w
7 S1 f
()1861 3031 w
1861 3031 m
27 build_ob
1888 3031 m
7 R f
(.)1594 3199 w
(.)1625 3178 w
(.)1655 3158 w
(.)1684 3137 w
(.)1715 3117 w
(.)1745 3096 w
(.)1774 3075 w
(.)1805 3055 w
(.)1835 3034 w
(.)1864 3014 w
7 S1 f
()2131 2845 w
2131 2845 m
27 build_ob
2158 2845 m
7 R f
(.)1864 3014 w
(.)1895 2993 w
(.)1925 2973 w
(.)1954 2952 w
(.)1985 2931 w
(.)2015 2911 w
(.)2044 2890 w
(.)2075 2870 w
(.)2105 2849 w
(.)2134 2828 w
8 R f
(Scheme)2184 2845 w
10 R f
3720 4122 2640 4122 Dl
2640 2682 2640 4122 Dl
2774 4194 2774 4122 Dl
(5)2749 4304 w
3044 4194 3044 4122 Dl
(6)3019 4304 w
3314 4194 3314 4122 Dl
(7)3289 4304 w
3584 4194 3584 4122 Dl
(8)3559 4304 w
(Solaris)3041 2617 w
10 CW f
(k)3150 4442 w
2604 3815 2640 3815 Dl
2604 3509 2640 3509 Dl
2604 3202 2640 3202 Dl
2604 2896 2640 2896 Dl
7 S1 f
()2761 3800 w
2761 3800 m
27 build_ob
2788 3800 m
()3031 3661 w
3031 3661 m
27 build_ob
3058 3661 m
7 R f
(.)2764 3783 w
(.)2798 3766 w
(.)2832 3749 w
(.)2866 3731 w
(.)2900 3713 w
(.)2934 3696 w
(.)2967 3679 w
(.)3001 3662 w
(.)3034 3644 w
7 S1 f
()3301 3494 w
3301 3494 m
27 build_ob
3328 3494 m
7 R f
(.)3034 3644 w
(.)3065 3626 w
(.)3095 3607 w
(.)3124 3588 w
(.)3155 3569 w
(.)3185 3551 w
(.)3214 3533 w
(.)3245 3514 w
(.)3275 3495 w
(.)3304 3477 w
7 S1 f
()3571 3306 w
3571 3306 m
27 build_ob
3598 3306 m
7 R f
(.)3304 3477 w
(.)3335 3456 w
(.)3365 3435 w
(.)3394 3415 w
(.)3425 3394 w
(.)3455 3373 w
(.)3484 3352 w
(.)3515 3331 w
(.)3545 3310 w
(.)3574 3289 w
8 R f
(C)3624 3306 w
7 S1 f
()2761 3443 w
2761 3443 m
27 build_ob
2788 3443 m
()3031 3264 w
3031 3264 m
27 build_ob
3058 3264 m
7 R f
(.)2764 3426 w
(.)2795 3406 w
(.)2825 3387 w
(.)2854 3366 w
(.)2885 3347 w
(.)2915 3327 w
(.)2944 3307 w
(.)2975 3287 w
(.)3005 3267 w
(.)3034 3247 w
7 S1 f
()3301 3072 w
3301 3072 m
27 build_ob
3328 3072 m
7 R f
(.)3034 3247 w
(.)3065 3226 w
(.)3095 3204 w
(.)3124 3183 w
(.)3155 3161 w
(.)3185 3140 w
(.)3214 3119 w
(.)3245 3097 w
(.)3275 3076 w
(.)3304 3055 w
7 S1 f
()3571 2874 w
3571 2874 m
27 build_ob
3598 2874 m
7 R f
(.)3304 3055 w
(.)3335 3032 w
(.)3365 3011 w
(.)3394 2988 w
(.)3425 2967 w
(.)3455 2944 w
(.)3484 2923 w
(.)3515 2901 w
(.)3545 2879 w
(.)3574 2857 w
8 R f
(Awk)3624 2874 w
7 S1 f
()2761 3358 w
2761 3358 m
27 build_ob
2788 3358 m
()3031 3177 w
3031 3177 m
27 build_ob
3058 3177 m
7 R f
(.)2764 3341 w
(.)2795 3321 w
(.)2825 3301 w
(.)2854 3281 w
(.)2885 3261 w
(.)2915 3241 w
(.)2944 3221 w
(.)2975 3201 w
(.)3005 3181 w
(.)3034 3160 w
7 S1