Using Python 2.1 and Numeric 20.2.1 on Redhat Linux 7.1 Shouldn't masked arrays preserve the fill value of their operands, if both operands have the same fill value? Otherwise, if I want to preserve the value of the fill_value, I have to write expressions like: d=masked_values((a+b),a.fill_value()) Here's a demonstration of the problem:

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a = masked_values((1.0,2.0,3.0,4.0,-999.0), -999) b = masked_values((-999.0,1.0,2.0,3.0,4.0), -999)

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a array(data = [ 1., 2., 3., 4.,-999.,], mask = [0,0,0,0,1,], fill_value=-999)

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b array(data = [-999., 1., 2., 3., 4.,], mask = [1,0,0,0,0,], fill_value=-999)

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c=a+b c array(data = [ 1.00000002e+20, 3.00000000e+00, 5.00000000e+00, 7.00000000e+00, 1.00000002e+20,], mask = [1,0,0,0,1,], fill_value=[ 1.00000002e+20,])

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d=masked_values((a+b),a.fill_value()) d array(data = [-999., 3., 5., 7.,-999.,], mask = [1,0,0,0,1,], fill_value=-999) -- Joe VanAndel National Center for Atmospheric Research http://www.atd.ucar.edu/~vanandel/ Internet: vanandel@ucar.edu