galib bug list.htm

提供了遗传算法的一些代码库文件

  <LI>The <STRONG>read</STRONG> member function of 1D, 2D, and 3D binary string 
  genomes will cause a segmentation fault in cases where the genome has length 
  (width, height) of zero. The fix is to change the <CODE>do...while</CODE> loop 
  into a <CODE>while</CODE> loop. This should be done in GA1DBinStringGenome.C, 
  GA2DBinStringGenome.C, and GA3DBinStringGenome.C. <BR><BR>
  <LI>Examples 5 and 14 do not work correctly because the 
  <CODE>_evaluated</CODE> flag is not properly reset in the initialize, mutate, 
  and crossover methods. In any custom-defined genome, you must set 
  <CODE>_evaluated</CODE> to <CODE>gaFalse</CODE> whenever you change the state 
  of a genome, otherwise the genome's evaluator will not be invoked (the cached 
  score will be used instead). <BR><BR>
  <LI>On some platforms, using a GARealGenome with the GARealGaussianMutator 
  will occasionally result in a crash when GAUnitGaussian takes the square root 
  of a negative number. To be sure this never happens, change the following code 
  in garandom.C so that this: <PRE>101       } while(rsquare &gt;= 1.0 || rsquare == 0.0);
102
103       factor = sqrt( -2.0 * log(rsquare) / rsquare );
104
105       cachevalue = var1 * factor;
       </PRE>becomes this: <PRE>101       } while(rsquare &gt;= 1.0 || rsquare == 0.0);
102
          double val = -2.0 * log(rsquare) / rsquare;
          if(val &gt; 0.0) factor = sqrt(val);
          else           factor = 0.0;
104
105       cachevalue = var1 * factor;
       </PRE>
  <LI>In the DemeGA, changing the number of populations to a larger number after 
  the GA has been created will result in a segmentation fault. The nPopulations 
  member function should be modified as follows. Insert a line of code that 
  modifies the population in GADemeGA::nPopulations(unsigned int n) so that 
  this: <PRE>264         }
265         return npop;
266       }

       </PRE>becomes this: <PRE>264         }
            pop-&gt;size(npop);
265         return npop;
266       }
       </PRE>
  <LI>The PC and Mac GAlib packages have a typo in example 5. My PERL script for 
  converting UNIX to PC got a little carried away. Change: <PRE>69  CompositeGenome(int element, int bond, GABin2DecPhenotype&amp; p, 
70  		  GAGenome::Evaluator f, void* u) :
71  		  GAGenome.cppompositeInitializer,
72  			   CompositeMutator,
73			   CompositeComparator) {
       </PRE>to: <PRE>69  CompositeGenome(int element, int bond, GABin2DecPhenotype&amp; p, 
70		  GAGenome::Evaluator f, void* u) :
71		  GAGenome(CompositeInitializer,
72			   CompositeMutator,
73			   CompositeComparator) {
       </PRE></LI></UL><BR><BR><BR><BR><BR><STRONG>bugs in version 
2.4.1</STRONG></A><BR><SMALL><I>fixed in release 2.4.2</I></SMALL><BR>
<HR>

<UL>
  <LI>The random number seed may occasionally be set to 0, resulting in all 0s 
  from the GARandomBit function. This bug was introduced in the 2.4.1 release as 
  I tried to make the seed generator more robust with respect to various 
  implementations of 'time()' on different OSes. To fix the problem, make the 
  following change to random.C in the function GARandomSeed. Change line 56 
  from: <PRE>56    for(unsigned int i=0; i&lt;sizeof(unsigned int); i++) {
       </PRE>to: <PRE>56    for(unsigned int i=0; i&lt;BITS_IN_WORD * sizeof(unsigned int); i++) {
       </PRE>
  <LI>If you are compiling with NO_STREAMS defined, you will have to fix error.C 
  so that it includes stdio.h. Just move '#include &lt;stdio.h&gt;' so that it 
  is outside of the '#ifndef NO_STREAMS ... #endif' directive. 
  <LI>The filenames used in this distribution may conflict with system files. 
  For example, 'list.h' conflicts with Metrowerks' 'list.h' in Codewarrior 9 and 
  later, and 'tree.h' conflicts with borland's 'tree.h' in version 5.x of their 
  compiler. </LI></UL><BR><BR><BR><BR><BR><STRONG>bugs in version 
2.4</STRONG><BR><SMALL><I>fixed in release 2.4.1</I></SMALL><BR>
<HR>

<UL>
  <LI>The default population evaluator forces unnecessary genome evaluations. In 
  population.C, remove 'gaTrue' from the call to the genome 'evaluate' member 
  function in GAPopulation::DefaultEvaluator. 
  <LI>The GANode and GANodeBASE classes do not have virtual destructors, so any 
  classes derived from them do not destruct properly. 
  <LI>The statistics object does not work properly with genetic algorithms that 
  are configured to minimize. 'best' and 'worst' are reversed when minimizing 
  and the lowest score is not always maintained. 
  <LI>The simple genetic algorithm does not properly maintain the best 
  individual when minimizing. </LI></UL><BR><BR><BR><BR><BR><A 
name=version_2.3.2><STRONG>bugs in version 2.3.2</STRONG></A><BR>
<HR>

<UL>
  <LI>The <B>remove</B> method was never defined for the GABin2DecPhenotype 
  class in bin2dec.ph.C (it was declared in the header file). Ooops, sorry about 
  that. Upgrade to version 2.4. <BR><BR>
  <LI>A population size of 1 will cause a crash when the statistics are updated. 
  This has been fixed in the 2.4 release. <BR><BR>
  <LI>The <B>remove</B> member of the GATree class does not properly re-set the 
  node pointers on the subtree that is removed. To fix this problem, make the 
  following modifications to treetmpl.C: <PRE>69  if(node-&gt;prev != node) iter.eldest();
70  else if(node-&gt;parent) iter.parent();
71  else iter.node = (GANodeBASE *)0;
72  t-&gt;insert((GANode&lt;T&gt; *)GATreeBASE::remove(node), (GANode&lt;T&gt; *)0, 
73	    GATreeBASE::ROOT);
74
75  return t;
76 }
       </PRE>should be modified to <PRE>69  if(node-&gt;prev != node) iter.eldest();
70  else if(node-&gt;parent) iter.parent();
71  else iter.node = (GANodeBASE *)0;
    GANode&lt;T&gt; *tmpnode = (GANode&lt;T&gt;*)GATreeBASE::remove(node);
    tmpnode-&gt;prev = tmpnode;
    tmpnode-&gt;next = tmpnode;
    tmpnode-&gt;parent = (GANodeBASE *)0;
    t-&gt;insert(tmpnode, (GANode&lt;T&gt; *)0, GATreeBASE::ROOT);
74
75  return t;
76 }
       </PRE>
  <LI>The array swap and flip mutators have a bug in them that will prevent 
  mutation in some cases. To fix it, do the following. 
  <P>Change lines 83 and 114 in array1.op.C. The first change is in 
  GA1DArrayFlipMutator: <PRE>83     for(n=1; n&lt;nMut; n++){
</PRE>should be <PRE>83     for(n=0; n&lt;nMut; n++){
</PRE>The second change is in GA1DArraySwapMutator: <PRE>114    for(n=1; n&lt;nMut; n++)
</PRE>should be <PRE>114    for(n=0; n&lt;nMut; n++)
</PRE>
  <LI>Be careful with the random number generator. If you use GAlib right out of 
  the box, the GARandomBit function caches bits rather than calling the random 
  function multiple times. This may or may not be a problem, depending on the 
  underlying random function you use. The default configuration for GAlib is to 
  use your system's rand() or random() function to generate random numbers. 
  Typically, the system random number generators are not very robust. The actual 
  implementation varies from system to system, but most use some sort of linear 
  congruential generator, and you <I>should not</I> expect the bits of the 
  numbers these RNGs generate to be uniformly random. For many applications, the 
  default GAlib configuration will suffice, but if you are doing extensive 
  statistical evaluation of results obtained using GAlib you should consider 
  writing your own random number generator and plugging it in to replace rand() 
  or random(). You can do this by modifying random.h to use your random 
  function. 
  <P>See <A href="http://nr.harvard.edu/nr/bookc.html">Numerical Recipes in 
  C</A> for details about the issues of using various random number generators. 
  These issues have been resolved in the 2.4 release of GAlib. </P>
  <LI>The <B>scaling</B> member function of the GAPopulation object does not 
  properly update the scaling object when it is changed. If you try to change 
  the scaling during the course of an evolution, your program will crash (the 
  selector returns nil pointers after you change the selector). The 'evaluate' 
  member of the scaling object must be called before the selector accesses the 
  scaling data. 
  <P>In the <B>scaling</B> member function in population.C, add one line of code 
  so that <PRE>275  sm-&gt;resize(n);
276  return *sm;
</PRE>becomes <PRE>275  sm-&gt;resize(n);
     if(evaluated) sm-&gt;evaluate(*this);
276  return *sm;
</PRE>
  <LI>The <B>copy</B> member function of the GAPopulation object has a typo in 
  it. Whenever you try to copy a population, the copy member clones the worst 
  individual in the population rather than copying each individual in the 
  population. To fix the problem, change [0] to [i] as shown here. 
  <P>In population.C, change 0 to an i in line 153 so that <PRE>151  ind = new GAGenome * [N];
152  for(i=0; i&lt;n; i++)
153    ind[i] = arg.ind[<B>0</B>]-&gt;clone();
154
155  if(arg.sm) sm = arg.sm-&gt;clone();
</PRE>becomes <PRE>151  ind = new GAGenome * [N];
152  for(i=0; i&lt;n; i++)
153    ind[i] = arg.ind[<B>i</B>]-&gt;clone();
154
155  if(arg.sm) sm = arg.sm-&gt;clone();
</PRE>
  <LI>The <B>initialize</B> member function of any GA class must be called 
  <I>after</I> any calls to the <B>populationSize</B> member function, otherwise 
  the scaling object does not get updated and your GA will crash on its first 
  selection. This means that you cannot change the population size during the 
  course of an evolution. To fix the problem make the following changes: 
  <P>In population.C, insert a line and modify a line to change <PRE>209  sm-&gt;resize(pops);
210  statted = sorted = evaluated = gaFalse;
211  n = pops;
</PRE>to <PRE>209  sm-&gt;resize(pops);
210  statted = sorted = gaFalse;
211  n = pops;
     if(evaluated == gaTrue) evaluate(gaTrue);
</PRE>and in the file scaling.C, insert a single line to change <PRE>102  fitSum = fitAve = fitMax = fitMin = fitVar = fitDev = 0.0;
103  return(n = popsize);
</PRE>to <PRE>102  fitSum = fitAve = fitMax = fitMin = fitVar = fitDev = 0.0;
     evaluated = gaFalse;
103  return(n = popsize);
</PRE></LI></UL><BR><BR><BR><BR><BR><A name=version_2.3.1><STRONG>bugs in 
version 2.3.1</STRONG></A><BR>
<HR>

<UL>
  <LI>There was a typo in population.C. In the function <CODE>GAGenome * 
  GAPopulation::replace(GAGenome * repl, const int which)</CODE>, <PRE><CODE>
      if(sorted)
	rawMax = ind[n-1]-&gt;score();
      else if(orig-&gt;score() == rawMax){
	rawMax = ind[0]-&gt;score();
	for(i=1; i&lt;n; i++)
	  rawMax = Min(rawMax, ind[i]-&gt;score());
      }
      else
	rawMax = Max(rawMax, repl-&gt;score());
</CODE></PRE>The 'Min' should be 'Max': <PRE><CODE>          rawMax = Max(rawMax, ind[i]-&gt;score());
</CODE></PRE>
  <LI>Functions that return NULL would not compile with some compilers. 
  Functions that have this problem include member functions of the ListBASE and 
  List objects in listbase.h and listtmpl.h, and the TreeBASE and Tree objects 
  in treebase.h and treetmpl.h. ANSI C++ requires an explicit cast of NULL. 
  <LI>Many of the 'for' loops will not compile with some compilers. In some 
  cases, the loop variable is used outside the 'for' loop. Files with this 
  problem include allele.h, array1.op.C, binstr3.ch.C, ga.C, list.op.C, 
  population.C, scaling.C, selector.C, and many of the examples. ANSI C++ 
  specifies that a variable declared in a for loop loses scope after the loop 
  ends. 
  <LI>The population object does not initialize genomes when it is resized. 
  <LI>SimpleGA has a bug in it that delays convergence. A workaround is to use a 
  SteadyStateGA with 100% replacement. This will be only marginally slower than 
  using a bug-free SimpleGA. 
  <LI>Roundoff errors in the population object could lead to negative numbers 
  passed to the sqrt function. The fix is to check for a sign change before the 
  call to sqrt. The only way a sign change can occur is if there is a roundoff 
  error. (There are only two calls to sqrt in population.C. The error can only 
  occur in the sqrt call in the function <CODE>GAGenome * 
  GAPopulation::replace(GAGenome * repl, const int which)</CODE>) 
  <LI>The copy constructor for the GAObjectiveVector object did not initialize 
  the 'a' member to NULL </LI></UL></BODY></HTML>