NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Hi Al, I think I see the issue. Your fields are in Celsius, which is no big deal. Then, we use sub(a,b) or (a-b) to compute a temperature difference. Again, this is ok. So now we have a delta T in Celsius...and a 1 delta T in Celsius is also 1 delta T in Kelvin. It appears that the IDV computes the difference as a difference in Kelvin, then converts that value back to Celsius, since that is the unit of your original temperature field. I am pretty sure there is a way in the IDV to handle Temperature differences, but in this case, you can modify the formula and get it correct: sub(a,b)+273.15 This will ensure the values you get back from the formula are in Celsius. The values range between 19 C and 33 C, which is consistent with the values in the example grids you sent. Let me know if this works for you. Cheers! Sean > Thanks Sean, > I've got a display using the "sub" command, however the output values don't > appear to be correct. I'm getting values between -259.6 and -236.1 when i'm > expecting between -135 and 135. I get the same result when I use the preset > formula a-b. Any idea what might be going wrong here? > Cheers Al > > ________________________________________ > From: Unidata IDV Support [address@hidden] > Sent: Tuesday, 15 January 2013 7:22 AM > To: Mr Alister Hawksford > Cc: address@hidden > Subject: [IDV #JHR-169833]: Cannot create display from formula > > Greetings! > > Try using this for your formula: > > sub(a,b) / 350 > > I think because the grids are on two different vertical levels, you need to > use the > sub(a,b) routine to do the subtraction. > > Cheers! > > Sean > > > No problem Sean. > > I've uploaded the two datasets onto motherlode in two separate uploads > > addressed to you. The variables are: > > (a) temperature at the 850mb level (850temp.nc) > > (b) temperature at the 500mb level (500temp.nc) > > which relate to > > (a-b)/350 > > The domain and times are identical. > > Thanks for your time. > > > > ________________________________________ > > From: Unidata IDV Support [address@hidden] > > Sent: Tuesday, 15 January 2013 3:38 AM > > To: Mr Alister Hawksford > > Cc: address@hidden > > Subject: [IDV #JHR-169833]: Cannot create display from formula > > > > Greetings Alister, > > > > Is there any way we could get a sample of your data to see exactly what is > > going on? Also, > > could you tell us which variables you are subtracting? If you don't mind > > sending some > > example data, please upload it here: > > > > http://motherlode.ucar.edu/repository/alias/idvupload > > > > Thanks! > > > > Sean > > > > > Full Name: Alister Hawksford > > > Email Address: address@hidden > > > Organization: Bureau of Meteorology > > > Package Version: 3.1u1 build date:2012-11-30 17:36 UTC > > > Operating System: Windows Vista > > > Hardware: Java: home: C:\Program Files\IDV_3.1u1\jre version: 1.6.0_31 > > > j3d:1.5.2 fcs (build4) > > > Description of problem: Creating display: Color-Filled Contour Plan View > > > visad.SetException: visad.SetException: Gridded3DSet.valueToGrid: > > > ManifoldDimension must be 3 > > > Gridded3DSet.valueToGrid: ManifoldDimension must be 3 > > > > > > To whom it may concern, > > > I have been following the Unidata instructions for formula creation > > > (http://www.unidata.ucar.edu/software/idv/docs/workshop/formulas/SimpleFormulas.html) > > > and I have not been able to display my formula as follows: > > > (a-b)/(850-500) > > > Could you please explain what the above error code means and how I might > > > solve it? > > > Thank you for your help. > > > > > > ****************** > > > Stack trace: > > > visad.SetException: Gridded3DSet.valueToGrid: ManifoldDimension must be 3 > > > at visad.Gridded3DSet.valueToGrid(Gridded3DSet.java:1070) > > > at visad.Gridded3DSet.valueToIndex(Gridded3DSet.java:418) > > > at visad.FlatField.resample(FlatField.java:4737) > > > at visad.FlatField.binary(FlatField.java:2085) > > > at visad.FieldImpl.binary(FieldImpl.java:836) > > > at visad.DataImpl.binary(DataImpl.java:139) > > > at visad.DataImpl.subtract(DataImpl.java:192) > > > at visad.DataImpl.__sub__(DataImpl.java:1400) > > > at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) > > > at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) > > > at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) > > > at java.lang.reflect.Method.invoke(Unknown Source) > > > at > > > org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java:186) > > > at > > > org.python.core.PyReflectedFunction.__call__(PyReflectedFunction.java:204) > > > at org.python.core.PyObject.__call__(PyObject.java:404) > > > at org.python.core.PyObject.__call__(PyObject.java:408) > > > at org.python.core.PyMethod.__call__(PyMethod.java:124) > > > at org.python.core.PyMethod.__call__(PyMethod.java:115) > > > at org.python.core.PyObjectDerived.__sub__(PyObjectDerived.java:187) > > > at org.python.core.PyObject._basic_sub(PyObject.java:2119) > > > at org.python.core.PyObject._sub(PyObject.java:2105) > > > at org.python.pycode._pyx109.f$0(<string>:1) > > > at org.python.pycode._pyx109.call_function(<string>) > > > at org.python.core.PyTableCode.call(PyTableCode.java:165) > > > at org.python.core.PyCode.call(PyCode.java:18) > > > at org.python.core.Py.runCode(Py.java:1261) > > > at org.python.core.__builtin__.eval(__builtin__.java:484) > > > at org.python.core.__builtin__.eval(__builtin__.java:488) > > > at org.python.util.PythonInterpreter.eval(PythonInterpreter.java:190) > > > at ucar.unidata.data.DerivedDataChoice.getData(DerivedDataChoice.java:782) > > > at ucar.unidata.data.DataChoice.getData(DataChoice.java:637) > > > at ucar.unidata.data.DataInstance.getData(DataInstance.java:243) > > > at ucar.unidata.data.DataInstance.getData(DataInstance.java:207) > > > at ucar.unidata.data.grid.GridDataInstance.init(GridDataInstance.java:205) > > > at > > > ucar.unidata.data.grid.GridDataInstance.<init>(GridDataInstance.java:162) > > > at > > > ucar.unidata.data.grid.GridDataInstance.<init>(GridDataInstance.java:143) > > > at > > > ucar.unidata.idv.control.GridDisplayControl.doMakeDataInstance(GridDisplayControl.java:284) > > > at > > > ucar.unidata.idv.control.DisplayControlImpl.initializeDataInstance(DisplayControlImpl.java:3176) > > > at > > > ucar.unidata.idv.control.DisplayControlImpl.setData(DisplayControlImpl.java:3158) > > > at > > > ucar.unidata.idv.control.PlanViewControl.setData(PlanViewControl.java:641) > > > at > > > ucar.unidata.idv.control.ContourPlanViewControl.setData(ContourPlanViewControl.java:194) > > > at ucar.unidata.idv.control.PlanViewControl.init(PlanViewControl.java:471) > > > at > > > ucar.unidata.idv.control.DisplayControlImpl.init(DisplayControlImpl.java:1419) > > > at > > > ucar.unidata.idv.control.DisplayControlImpl.init(DisplayControlImpl.java:1102) > > > at > > > ucar.unidata.idv.ControlDescriptor.initControl(ControlDescriptor.java:986) > > > at ucar.unidata.idv.ControlDescriptor$1.run(ControlDescriptor.java:911) > > > at ucar.unidata.util.Misc$3.run(Misc.java:1250) > > > > > > > > > > > > > Ticket Details > > =================== > > Ticket ID: JHR-169833 > > Department: Support IDV > > Priority: Normal > > Status: Open > > > > > > > > > > Ticket Details > =================== > Ticket ID: JHR-169833 > Department: Support IDV > Priority: Normal > Status: Open > > > > Ticket Details =================== Ticket ID: JHR-169833 Department: Support IDV Priority: Normal Status: Open