Re: Units problem

• To: Eugene Tan <chet@xxxxxxxxxx>
• Subject: Re: Units problem
• From: "From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>" <billh@xxxxxxxxxxxxx>
• Date: Wed, 12 Jan 2000 11:21:53 -0600 (CST)

Dear Eugene,

I am still having trouble figuring exactly what it is you
are doing, to reproduce your error.  For example, I don't
know how the 'RealTuple selectedTuple' argument to printTuple
relates to your FlatField.

Could you please put together a complete program that
illustrates the problem, and put it on a server for us.
If necessary, use our anonymous incoming ftp at:

  ftp://hyde.ssec.wisc.edu/pub/incoming

Then please send me an email telling me the names of the
files, and how to run them.  We should probably finish this
discussion off the list.

Cheers,
Bill
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI  53706
hibbard@xxxxxxxxxxxxxxxxx  608-263-4427  fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html


On Tue, 11 Jan 2000, Eugene Tan wrote:

> Dear Bill,
> 
> I tried updating the source but it hasn't done anything. We still have the
> same problem. This is how we're printing out what's in the field which has
> worked for us from beginning to now.
> 
> public static void printTuple(RealTuple selectedTuple)
>     throws VisADException, RemoteException {
> 
>     Unit[] unitArray = selectedTuple.getTupleUnits();
>     int dimension = selectedTuple.getDimension();
> 
>     for (int i=0; i < dimension; i++) {
>         Real data = (Real)selectedTuple.getComponent(i);
>       
>         double dataValue = data.getValue();
>         System.out.print("\tComponent: " + i + " ");
>         System.out.print("\tType: " + data.getType() + " ");
>         System.out.print("\tValue: " + data.getValue() + " ");
>         System.out.print("\tUnits: " + data.getUnit());
>         System.out.print("\n");
>     }
> }
> 
> After looking further, I've found another problem. I'm trying to convert
> 20 degrees celsius into kelvin and then changing it back to celsius. This
> is the output I'm getting:
> 
> >From Celsius to Kelvin (looks like it works):
> Component: 0    Type: MinTemp   Value: 293.1499938964844 Units: K
> Component: 1    Type: MaxTemp   Value: 293.1499938964844 Units: K
> 
> And then when I convert it back Celsius using the same code:
> Component: 0    Type: MinTemp   Value: -253.14999389648438 Units: Cel
> Component: 1    Type: MaxTemp   Value: -253.14999389648438 Units: Cel
> 
> It looks like the program has deducted 273.15K from 20 degrees celsius?
> 
> This is how our code does it:
> 
> //field is the flatfield containing the original data
> float[][] values = field.getFloats();
> values = Unit.convertTuple(values, oldUnits, newUnits);
> 
> //newField is the flatfield we're creating now - the code to do this is in
> //my previous mail
> newField.setSamples(values);
> 
> Please tell me what I'm doing wrong as I'm stuck again. Do you have any
> suggestion of a better way?
> 
> Thanks in advance.
> 
> Eug.
> 
>    _--_|\     Eugene Tan <E.Tan@xxxxxxxxxx>
>   /      \    AutoTAF Project Developer 
>   \_.--.*/    Bureau of Meteorology, Melbourne, VIC 3001, Australia
>         v     Telephone: +613 9669 4652
> 
> On Mon, 10 Jan 2000, From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx> wrote:
> 
> > I'm not sure how you're printing the FlatField, but I did
> > find a bug in FlatField.toString() that could cause your
> > problem.  I am at the AMS Conference in Long Beach this
> > week and cannot update our source server, but did put the
> > fix at:
> > 
> >   ftp://hyde.ssec.wisc.edu/pub/incoming/FlatField.java
> > 
> > On Mon, 10 Jan 2000, Eugene Tan wrote:
> > 
> > > We can't seem to convert some units properly. This is what we have:
> > > 
> > > (in a for loop to print out the original units)
> > > Units: 
> > > oldUnits: Cel
> > > oldUnits: Cel
> > > oldUnits: degrees_north
> > > 
> > > We then change all the Cel (celsius) units to Kelvin by doing this:
> > > 
> > > Unit[] newUnits = Unit.copyUnitsArray(oldUnits);
> > > Unit toUnit = SI.kelvin;
> > > 
> > > for (int i=0; i < oldUnits.length; i++) {
> > >     if (newUnits[i].toString().equals("Cel")) {
> > >         newUnits[i]=toUnit;
> > >     }
> > > }
> > > 
> > > Printing out the new units array:
> > > (in a for loop to print out the new units)
> > > Units: 
> > > newUnits: K
> > > newUnits: K
> > > newUnits: degrees_north
> > > 
> > > We then create a FlatField ie.
> > > 
> > > FlatField newField
> > >     new FlatField((FunctionType) field.getType(),
> > >             field.getDomainSet(),
> > >             null, 
> > >             null,
> > >                     field.getRangeSets(),
> > >             newUnits);
> > > 
> > > When I printed out the contents of newField, this is the output I get:
> > > Component: 0    Type: MinTemp   Value: NaN      Units: Cel
> > > Component: 1    Type: MaxTemp   Value: NaN      Units: Cel
> > > Component: 2    Type: WindDir   Value: NaN      Units: degrees_north
> > > 
> > > which is wrong. We want to convert the units for Component 0 & 1 to
> > > Kelvin but it keeps returning "Cel". Can anyone identify what we're doing
> > > wrong please?
> 
> 

• References:
  • Re: Units problem
    • From: Eugene Tan