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Biasing

If the minimum data value in the dataset is less than or equal to zero, and the user selects log spacing of the data layers then there are obviously problems. ASMOOTH solves this by adding a bias value to the data minimum and maximum before calculating the logarithmically spaced data levels. Once calculated the bias value is subtracted off.

The default for the bias level is |dmin| + 1% * dmax. The value must clearly be at least as big as |dmin|, but if exactly that value is supplied then there are an infinite number of logarithmic decades between (dmin+bias) and dmax. ASMOOTH adds on another 1% of the data range, which will reduces the dynamic range in the data to two decades. By adding on smaller percentages of the data range in response to the BIAS prompt (ie. values less than the default but larger than |dmin|) a larger dynamic range will be retained.

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