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comparison extra/testfun/speed.m @ 0:6b33357c7561 octave-forge

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Initial revision
author pkienzle
date Wed, 10 Oct 2001 19:54:49 +0000
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1 ## Copyright (C) 2000-2001 Paul Kienzle
2 ##
3 ## This program is free software; you can redistribute it and/or modify
4 ## it under the terms of the GNU General Public License as published by
5 ## the Free Software Foundation; either version 2 of the License, or
6 ## (at your option) any later version.
7 ##
8 ## This program is distributed in the hope that it will be useful,
9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 ## GNU General Public License for more details.
12 ##
13 ## You should have received a copy of the GNU General Public License
14 ## along with this program; if not, write to the Free Software
15 ## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
16
17 ## speed(f, init, max_n, f2, tol, err)
18 ##
19 ## Determine the execution time of an expression for various n.
20 ## The n are log-spaced from 1 to max_n. For each n, an
21 ## initialization expression is computed to create whatever
22 ## data are needed for the test.
23 ##
24 ## f is the expression to evaluate.
25 ## max_n = 100 is the maximum test length to run.
26 ## init = "x = randn(n, 1);"
27 ## Initialization expression for function argument values. Use 'k'
28 ## for the test number and 'n' for the size of the test. This should
29 ## compute values for all variables listed in args. Note that init
30 ## will be evaluated first for k=0, so things which are constant
31 ## throughout the test can be computed then.
32 ## f2 = []
33 ## is an alternative expression to evaluate, so the speed of the two
34 ## can be compared
35 ## tol = eps
36 ## if tol is inf, then no comparison will be made between the
37 ## results of express f and expression f2. Otherwise, expression
38 ## f should produce a value v and expression f2 should produce
39 ## a value v2, and these shall be compared using assert(v,v2,tol,err)
40 ##
41 ## r = speed (...)
42 ## Returns the average speedup ratio instead of displaying and plotting.
43 ##
44 ## Some global variables are also referenced. Choose values suitable to
45 ## your machine and your work style.
46 ## speed_test_plot = 1
47 ## if true, plot a nice speed comparison graph
48 ## speed_test_numtests = 25
49 ## number of vector lengths to test
50 ##
51 ## Some comments on the graphs. The line on the speedup ratio graph
52 ## should be larger than 1 if your function is faster. The slope on
53 ## the runtime graph shows you the O(f) speed characteristics. Where it
54 ## is flat, execution time is O(1). Where it is sloping, execution time
55 ## is O(n^m), with steeper slopes for larger n. Generally vectorizing
56 ## a function will not change the slope of the run-time graph, but it
57 ## will shift it relative to the original.
58 ##
59 ## Example
60 ## % If you had an original version of xcorr using for loops and
61 ## % another version using FFT, you could compare the run speed
62 ## % for various lags as follows, or for a fixed lag with varying
63 ## % vector lengths as follows:
64 ##
65 ## speed("v=xcorr(x,n)", "x=rand(128,1);", 100, ...
66 ## "v2=xcorr_orig(x,n)", 100*eps,'rel')
67 ## speed("v=xcorr(x,15)", "x=rand(20+n,1);", 100, ...
68 ## "v2=xcorr_orig(x,n)", 100*eps,'rel')
69 ##
70 ## % Assuming one of the two versions is in xcorr_orig, this would
71 ## % would compare their speed and their output values. Note that the
72 ## % FFT version is not exact, so we specify an acceptable tolerance on
73 ## % the comparison (100*eps), and the errors should be computed
74 ## % relatively, as abs( (x-y)./y ) rather than absolutely as abs(x-y).
75 ##
76 ## Example
77 ## speed("strrep(s,x,y)", "s=blanks(n);x=' ';y='b';", 100)
78 ##
79 ## Type example('speed') to see some real examples. Note for
80 ## obscure reasons, you can't run examples 1 and 2 directly using
81 ## demo('speed'). Instead use:
82 ## eval(example('speed',1))
83 ## eval(example('speed',2))
84
85 ## TODO: consider two dimensional speedup surfaces for functions like kron.
86 function __ratio_r = speed (__f1, __init, __max_n, __f2, __tol, __err)
87 if nargin < 1 || nargin > 6,
88 usage("speed_test(f, init, max_n, f2, tol, err)");
89 endif
90 if nargin < 2 || isempty(__init),
91 __init = "x = randn(n, 1);";
92 endif
93 if nargin < 3 || isempty(__max_n), __max_n = 100; endif
94 if nargin < 4, __f2 = []; endif
95 if nargin < 5 || isempty(__tol), __tol = eps; endif
96 if nargin < 6 || isempty(__err), __err = []; endif
97
98 global speed_test_plot = 1;
99 global speed_test_numtests = 25;
100
101 __test_n = uniq(round(logspace(0,log10(__max_n),speed_test_numtests)));
102 __torig = __tnew = zeros (size(__test_n)) ;
103
104 disp (["testing..........", __f1, "\ninit: ", __init]);
105
106 ## make sure the functions are freshly loaded by evaluating them at
107 ## test_n(1); firt have to initialize the args though.
108 n=1; k=0;
109 eval ([__init, ";"]);
110 if !isempty(__f2), eval ([__f2, ";"]); endif
111 eval ([__f1, ";"]);
112
113 ## run the tests
114 for k=1:length(__test_n)
115 if (k > 1)
116 n=__test_n(k);
117 eval ([__init, ";"]);
118 endif
119
120 printf ("n%i=%i ",k, n) ; fflush(1);
121
122 eval (["__t=time();", __f1, "; __v1=ans; __t = time()-__t;"]);
123 if (__t < 0.25)
124 eval (["__t2=time();", __f1, "; __t2 = time()-__t2;"]);
125 eval (["__t3=time();", __f1, "; __t3 = time()-__t3;"]);
126 __t = min([__t,__t2,__t3]);
127 endif
128 __tnew(k) = __t;
129
130 if !isempty(__f2)
131 eval (["__t=time();", __f2, "; __v2=ans; __t = time()-__t;"]);
132 if (__t < 0.25)
133 eval (["__t2=time();", __f2, "; __t2 = time()-__t2;"]);
134 eval (["__t3=time();", __f2, "; __t3 = time()-__t3;"]);
135 endif
136 __torig(k) = __t;
137 if !isinf(__tol)
138 assert(__v1,__v2,__tol,__err);
139 endif
140 endif
141
142 end
143
144 if !isempty(__f2),
145 # Don't keep zero times
146 idx = find ( __tnew>sqrt(eps) & __torig>sqrt(eps) ) ;
147 ratio = mean (__torig(idx) ./ __tnew(idx));
148 if (nargout == 1)
149 __ratio_r = ratio;
150 else
151 printf ("\nmean runtime ratio of %s / %s : %g\n", __f2, __f1, ratio);
152 endif
153 else
154 if (nargout == 1)
155 _ratio_r = mean(__tnew);
156 else
157 printf ("\nmean runtime: %g\n", mean(__tnew));
158 endif
159 endif
160
161 if (speed_test_plot && nargout == 0 && !isempty(__f2))
162
163 if (gnuplot_has_multiplot) subplot(121); endif
164 xlabel("test length");
165 title (__f1);
166 ylabel("speedup ratio");
167 semilogx ( __test_n(idx), __torig(idx)./__tnew(idx) ,
168 ["-*r;", strrep(__f1,";","."), "/", strrep(__f2,";","."), ";"],
169 __test_n(idx), __tnew(idx)./__torig(idx) ,
170 ["-*g;", strrep(__f2,";","."), "/", strrep(__f1,";","."), ";"]);
171 if (gnuplot_has_multiplot)
172 subplot (122);
173 else
174 input ("Press any key for the next graph:", "s");
175 endif
176
177 ## convert best execution time to milliseconds.
178 __torig = 1000*__torig;
179 __tnew = 1000*__tnew;
180
181 ylabel ("best execution time (ms)");
182 title (["init: ", __init]);
183 loglog ( __test_n (idx), __tnew (idx), ["*-g;", strrep(__f1,";","."), ";" ],
184 __test_n (idx), __torig (idx), ["*-r;", strrep(__f2,";","."), ";"])
185 title (""); xlabel (""); ylabel (""); oneplot();
186 elseif (speed_test_plot && nargout == 0)
187 __tnew = 1000*__tnew;
188 xlabel("test length");
189 ylabel ("best execution time (ms)");
190 title ([__f1, " init: ", __init]);
191 loglog ( __test_n, __tnew, "*-g;;");
192 title (""); xlabel (""); ylabel (""); oneplot();
193 endif
194
195 endfunction
196
197 %!demo if 1
198 %! function x = build_orig(n)
199 %! ## extend the target vector on the fly
200 %! for i=0:n-1, x([1:10]+i*10) = 1:10; endfor
201 %! endfunction
202 %! function x = build(n)
203 %! ## preallocate the target vector
204 %! if (prefer_column_vectors), x = zeros(n*10, 1);
205 %! else x = zeros(1, n*10); endif
206 %! for i=0:n-1, x([1:10]+i*10) = 1:10; endfor
207 %! endfunction
208 %!
209 %! disp("-----------------------");
210 %! type build_orig;
211 %! disp("-----------------------");
212 %! type build;
213 %! disp("-----------------------");
214 %!
215 %! disp("Preallocated vector test.\nThis takes a little while...");
216 %! speed('build', 'build_orig', 1000, 'v=n;');
217 %! clear build build_orig
218 %! disp("Note how much faster it is to pre-allocate a vector.");
219 %! disp("Notice the peak speedup ratio.");
220 %! clear build build_orig
221 %! endif
222
223 %!demo if 1
224 %! function x = build_orig(n)
225 %! for i=0:n-1, x([1:10]+i*10) = 1:10; endfor
226 %! endfunction
227 %! function x = build(n)
228 %! idx = [1:10]';
229 %! x = idx(:,ones(1,n));
230 %! if (prefer_column_vectors), x = reshape(x, n*10, 1);
231 %! else x = reshape(x, 1, n*10); endif
232 %! endfunction
233 %!
234 %! disp("-----------------------");
235 %! type build_orig;
236 %! disp("-----------------------");
237 %! type build;
238 %! disp("-----------------------");
239 %!
240 %! disp("Vectorized test. This takes a little while...");
241 %! speed('build', 'build_orig', 1000, 'v=n;');
242 %! clear build build_orig
243 %! disp("-----------------------");
244 %! disp("This time, the for loop is done away with entirely.");
245 %! disp("Notice how much bigger the speedup is then in example 1.");
246 %! endif