<div dir="ltr"><div><div><div>You have rows of 0.0 ... I think that is causing issues. I'm sure some 'math-whiz' could answer but I attached a simple test code that reads your data (thx for providing). It calculates the inverse and the identity matrix. Note that NCL is using a direct call to the documented LAPACK routines.<br><br>===<br></div>TEST1: duplicates your findings<br><br></div>TEST 2: create a bogus 20x20 array of random numbers. No row consists of all constants. Identity matrix is successfully calculated.<br><br></div>TEST 3: wherever the original array had a row of all 0.0, substitute random numbers. The identity matrix is successfully calculated.</div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Nov 10, 2014 at 1:57 PM, Walter Hannah <span dir="ltr"><<a href="mailto:whannah@atmos.colostate.edu" target="_blank">whannah@atmos.colostate.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Hi,<br>
<br>
I'm trying to use the "inverse_matrix" function. The matrix doesn't
have any missing values, but I still get this error message:<br>
<blockquote><tt>Variable: M</tt><tt><br>
</tt><tt>Type: float</tt><tt><br>
</tt><tt>Total Size: 1600 bytes</tt><tt><br>
</tt><tt> 400 values</tt><tt><br>
</tt><tt>Number of Dimensions: 2</tt><tt><br>
</tt><tt>Dimensions and sizes: [pertlev | 20] x [tendlev | 20]</tt><tt><br>
</tt><tt>Coordinates:</tt><tt><br>
</tt><tt> pertlev: [50..1950]</tt><tt><br>
</tt><tt> tendlev: [50..1950]</tt><tt><br>
</tt><tt>Number Of Attributes: 2</tt><tt><br>
</tt><tt> missing_value : 9.96921e+36</tt><tt><br>
</tt><tt> _FillValue : 9.96921e+36</tt><tt><br>
</tt><tt>(0)
----------------------------------------------------------------------------</tt><tt><br>
</tt><tt><br>
</tt><tt> 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00<br>
0.00 -0.31 -0.06 0.15 -0.27 -0.56 -1.21 -1.38
-1.36 1.49 0.00 0.00 4.65 0.37 0.46 0.47 0.52
0.55 0.77 2.49<br>
0.00 0.26 -0.35 -0.29 -0.65 -1.13 -2.24 -2.45
-2.47 2.91 0.00 0.00 4.07 2.45 0.95 0.87 0.90
1.05 1.55 4.81<br>
0.00 -0.11 1.43 -0.91 -1.69 -1.52 -2.63 -2.81
-2.69 3.17 0.00 0.00 -2.35 2.61 1.49 1.01 1.00
1.18 1.78 5.32<br>
0.00 -0.02 0.55 1.08 -1.74 -2.04 -2.59 -2.71
-2.39 2.63 0.00 0.00 -0.75 -1.10 1.35 1.02 0.89
1.00 1.57 4.87<br>
0.00 -0.06 0.16 0.52 0.72 -1.86 -2.88 -2.74
-2.29 2.31 0.00 0.00 0.31 -1.30 -0.26 0.87 0.75
0.82 1.27 4.50<br>
0.00 -0.13 -0.07 0.20 0.54 0.27 -2.74 -3.10
-2.27 2.04 0.00 0.00 0.08 -0.49 -0.47 0.14 0.72
0.69 1.13 4.24<br>
0.00 -0.15 -0.06 0.20 -0.17 0.02 -0.77 -3.87
-3.13 2.39 0.00 0.00 0.69 -0.08 0.09 0.03 0.36
0.90 1.29 4.59<br>
0.00 -0.14 0.05 0.09 -0.17 -0.29 -0.14 -0.66
-5.36 2.00 0.00 0.00 0.39 0.17 0.14 0.07 -0.01
0.22 1.00 4.05<br>
0.00 0.02 -0.07 -0.01 0.00 0.02 0.43 0.94 0.77
-2.90 0.00 0.00 -0.09 0.09 -0.04 -0.07 -0.17 -0.26
-0.49 0.54<br>
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00<br>
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00<br>
0.00 -0.01 -0.04 0.12 -0.02 -0.01 -0.03 -0.05
-0.05 0.04 0.00 0.00 -2.17 -0.25 -0.14 0.01 0.02
0.02 0.02 0.12<br>
0.00 0.00 -0.19 0.11 0.28 0.06 0.11 0.06 0.07
-0.13 0.00 0.00 2.75 -1.97 -0.04 -0.12 -0.05 -0.05
-0.08 -0.10<br>
0.00 -0.02 -0.14 -0.08 0.31 0.21 0.13 0.08 0.06
-0.08 0.00 0.00 0.48 1.11 -1.09 -0.13 -0.10 -0.06
-0.09 -0.12<br>
0.00 -0.01 -0.03 -0.11 -0.07 0.32 0.27 0.12 0.18
-0.17 0.00 0.00 0.02 0.63 0.52 -0.94 -0.02 -0.15
-0.08 -0.25<br>
0.00 0.02 0.08 -0.06 -0.24 0.10 0.43 0.26 0.16
-0.17 0.00 0.00 0.07 0.31 0.35 0.40 -1.06 -0.06
-0.20 -0.26<br>
0.00 0.06 0.03 -0.10 0.07 0.11 1.03 1.38 0.53
-1.10 0.00 0.00 -0.44 0.14 -0.03 0.08 0.19 -1.61
-0.76 -1.16<br>
0.00 0.11 -0.03 -0.08 0.07 0.16 0.46 1.28 1.65
-1.21 0.00 0.00 -0.25 0.07 -0.06 0.00 0.14 0.41
-3.04 -0.66<br>
0.00 0.12 -0.30 -0.15 0.80 1.58 2.86 3.62 5.02
-3.15 0.00 0.00 -1.23 -0.91 -0.80 -0.94 -0.85 -0.66
0.21 -10.64<br>
<br>
(0)
----------------------------------------------------------------------------<br>
(0) # missing values: 0<br>
(0) # values = 0.0 : 111</tt><tt><br>
</tt><tt>warning:inverse_matrix: info = 1; missing values not
allowed</tt><br>
</blockquote>
<br>
I thought it might have something to do with those zero values, but
if I replace them with non-zero values I get a similar, but not
identical, result:<br>
<blockquote><tt>...<br>
(0)
----------------------------------------------------------------------------</tt><tt><br>
</tt><tt>(0) # missing values: 0</tt><tt><br>
</tt><tt>(0) # values = 0.0 : 0</tt><tt><br>
</tt><tt>warning:inverse_matrix: info = 20; missing values not
allowed</tt><br>
</blockquote>
<br>
<br>
Thanks,<br>
Walter
</div>
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<br></blockquote></div><br></div>