This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
Hi Tyn- > Thanks, sounds wonderful. No problems. It's more complete this way. > According to this example Tom provides the variable should already have an > error attached before an operation is preformed (see first two lines): > > a = new Real(10.,1.); > b = new Real(255.,10.); > c = (Real) a.add(b, Data.NEAREST_NEIGHBOR, Data.INDEPENDENT); > System.out.println("sum = "+c); > System.out.println("error of sum is="+c.getError().getErrorValue()); > When you run this example, you get: > sum = 265.0 > error of sum is=10.04987562112089 > > How do I provide the error FieldImpl along with the FieldImpl, should this be > done before I perform sampleToReal? When you call setSamples on the FieldImpl, you would pass in the ErrorEstimate. I'll have to get more info on what that will look like. > As i wrote earlier: I have a seperate error-field along with the FieldImpl i > do the GridUtil.sampleToReal on. The two FieldImpl share the same > time-dimension as they're from the same ADDE imageSeq. So, do you have an error value for each point in the image? Or is it an error per image? Don > -----Original Message----- > From: Unidata IDV Support [mailto:address@hidden] > Sent: Tuesday, February 23, 2010 5:24 PM > To: Valentijn Venus > Cc: address@hidden > Subject: [IDV #MQM-696970]: visad error propagation facility > > Hi Tyn- > > > Further to my previous message, I already found some answers to some of my > > questions. However, can you comment on the ??? below. > > > > > What are the numerical equivalents for the other propagations methods to > > > set int errorMode correctly? > > > > Data.NO_ERROR = 202 > > Data.INDEPENDENT = ??? > > Data.DEPENDENT = ??? > > Data.INDEPENDENT = 200 > Data.DEPENDENT = 201 > > I've added the following to GridUtil so you can use them there: > > public static final int NO_ERRORS = Data.NO_ERRORS; > public static final int DEPENDENT_ERRORS = Data.DEPENDENT; > public static final int INDEPENDENT_ERRORS = Data.INDEPENDENT; > > I've also added an error mode to the sampleToReal. sample already had the > error mode signature. > > These will be in tomorrow's build. > > > http://www.unidata.ucar.edu/software/idv/docs/javadoc/constant-values.html#ucar.unidata.data.grid.GridUtil.DEFAULT_ERROR_MODE > > > > > Is there a javadoc showing all propagations methods? > > > > NO, except this snippet in > > http://www.unidata.ucar.edu/mailing_lists/archives/visad/2002/msg00170.html: > > > > > > > Also, I can see that Data.INDEPENDENT uses a linear 'error > > > propagation' algorithm, but what does actually Data.DEPENDENT do (doesn't > > > one need to know the functional form of the dependency?). Is there any > > > auxiliary documentation somewhere, or references to the algorithms used? > > > > For Data.DEPENDENT the system uses the worst case error > > propagation, where they are simply added. This is essentially > > interval arithmetic. For Data.INDEPENDENT the system uses > > root mean square error propagation. > > I don't know any more than what was in that message. As Bill pointed out, > this has not been tested very well. I have no experience using the error > propagation, but if you run into problems, we can muddle along together. ;-) > > Don > > > -----Original Message----- > > From: Unidata IDV Support [mailto:address@hidden] > > Sent: Wednesday, May 13, 2009 12:25 AM > > To: Valentijn Venus > > Cc: address@hidden > > Subject: [IDV #MQM-696970]: visad error propagation facility > > > > Hi Tyn- > > > > > thanks! > > > > > > Unfortunately, not everything is done with visad. > > > > It will be difficult to do the error propagation fully then. > > > > > On the IDV side, would it take a lot of work to for all methods to pass > > > an error propagation type other than Data.NO_ERROR? Do you think Willem > > > could handle such a task? > > > > You'd need a way for the user to set the error mode and then modify all the > > methods in GridUtil that take a sampling method to also take an error mode. > > I took a stab at the latter, but not sure I got all the methods yet. Then > > any of the controls/methods that do sampling would need to implement this > > as well. > > > > I'm sure there are other gotcha's out there. We're in the middle of > > finalizing the 2.7 release, so don't have time to work on this. If > > Willem wants to look into it I can try to answer some of his questions. > > > > Don > > > > > > Ticket Details > > =================== > > Ticket ID: MQM-696970 > > Department: Support IDV > > Priority: Normal > > Status: Open > > > > > > Internal Virus Database is out of date. > > Checked by AVG - http://www.avg.com > > Version: 8.0.176 / Virus Database: 270.9.17/1845 - Release Date: 12/12/2008 > > 9:02 AM > > Faculty of Geo-Information Science and Earth Observation (ITC) > > University of Twente > > > > E-mail disclaimer > > The information in this e-mail, including any attachments, is intended for > > the addressee only. If you are not the intended recipient, you are hereby > > notified that any disclosure, copying, distribution or action in relation > > to the content of this information is strictly prohibited. If you have > > received this e-mail by mistake, please delete the message and any > > attachment and inform the sender by return e-mail. ITC accepts no liability > > for any error or omission in the message content or for damage of any kind > > that may arise as a result of e-mail transmission. > > > > > > > Ticket Details > =================== > Ticket ID: MQM-696970 > Department: Support IDV > Priority: Normal > Status: Open > > Faculty of Geo-Information Science and Earth Observation (ITC) > University of Twente > > E-mail disclaimer > The information in this e-mail, including any attachments, is intended for > the addressee only. If you are not the intended recipient, you are hereby > notified that any disclosure, copying, distribution or action in relation to > the content of this information is strictly prohibited. If you have received > this e-mail by mistake, please delete the message and any attachment and > inform the sender by return e-mail. ITC accepts no liability for any error or > omission in the message content or for damage of any kind that may arise as a > result of e-mail transmission. > > Ticket Details =================== Ticket ID: MQM-696970 Department: Support IDV Priority: Normal Status: Open