Page History

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67/171 for multi-lateration and 6/171 for tri-lateration.

Wiki MarkupNaN (Not a Number) is a value of numeric data-type representing an undefined or unrepresentable value, especially in floating point calculations. Reference and more \[here\|[http://en.wikipedia.org/wiki/NaN|http://en.wikipedia.org/wiki/NaN]\]More here.

According to the CBG code NaNs represent "bad pairs that lead to no region". This means that landmarks that fail to produce intersection regions, consequently also fail to produce an estimate for the location of the target and instead giving out an erroneous value. Author has handled such values with NaN (code snippet below).

if constraintType
  warning('Trying speed of light')
  constraintType = 0;
  % switch the constraint type and try again
  [locest,actual,error,regarea,distNearestLandmark,target_id,constraintType,inRegion\] = geolocate(file,extension,hullbool, constraintType, bestlineTable);
  return;
else
  % find the badPairs that lead to no region, write them to stdout
  badPairs = analyzeNoRegion( measurements )
  %error(\['No SOL intersection region for ', char(file)\])
  region = \[NaN NaN\];
  locest = \[NaN NaN\];
  error = NaN;
  regarea = NaN;
  results = \[target_id error; distNearestLandmark regarea; locest; actual; region\];
  dlmwrite(\[char(file),char(extension)\],results,' ');
  return;
end;

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2. Some results have enormous errors (|error|>1000)

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This is true for both multi-lateration and tri-lateration. And reasons could be one or more of the following:

• Number of landmarks aren't enough i.e. only 3 or 2 or less.
• Number of landmarks aren't enough and those which are present are duplicates.
• There are enough number of landmarks but none are good enough i.e. the RTT is in the order of 50+ ms (true for error distances in the order of thousands of km).
• There are enough number of landmarks but mostly aren't good enough i.e. the RTT is in the order of 25+ ms (true for error distances in the order of 1000+ km).

I've inferred these from looking at the Target files.

3. Tri-lateration is performing better than multi-lateration

There are 37 instances where tri-lateration performs better than multi-lateration, 26 instances where multi-lateration performs better than tri-lateration and in the rest both perform equally well. Reason??