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Defect in maximum calculation #3
Description
A standard pattern is used for maximum calculation:
double maxValue = Double.MIN_VALUE;
for (int nextAction : actionsFromState) {
double value = Q[nextState][nextAction];
if (value > maxValue)
maxValue = value;
}But Double.MIN_VALUE in Java is not minimal double but minimal positive value. See https://stackoverflow.com/questions/3884793/why-is-double-min-value-in-not-negative for details.
Especially, if each value considered in for-loop is 0, calculated maximum is Double.MIN_VALUE, because Double.MIN_VALUE > 0.
However, replacing Double.MIN_VALUE with Double.NEGATIVE_INFINITY cause wrong calculation. In such case maxQ(8) is Double.NEGATIVE_INFINITY and whole calculation fails.
Summary: maximum calculation is implemented wrong or at least misleading. It hard to me to propose a solution because it is not clear to me what is expected to be maxQ(8)
Reacted by technobium
Activity
ahsan-ikram commentedon Jun 18, 2018
I checked the code and I found the same issue as described above. Please use double maxValue = Double.NEGATIVE_INFINITY otherwise condition is never satisfied when it should be
if (value > maxValue)
maxValue = value;
technobium commentedon Jun 28, 2018
Thanks for the observation. I changed the code.
SimonAsenime commentedon Aug 2, 2018
While testing your code, I found that having double maxValue = Double.NEGATIVE_INFINITY throws off the whole calculation. Using Double.MIN_VALUE should fix things. Well, it runs perfect using MIN_VALUE anyway.