Search Results

Search found 5157 results on 207 pages for 'checking'.

Page 66/207 | < Previous Page | 62 63 64 65 66 67 68 69 70 71 72 73  | Next Page >

  • Find location using only distance and bearing?

    - by pinnacler
    Triangulation works by checking your angle to three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and it's to my right at 90 degrees." Repeat 2 more times for different targets and angles. Trilateration works by checking your distance from three KNOWN targets. "I know the that's the Lighthouse of Alexandria, it's located here (X,Y) on a map, and I'm 100 meters away from that." Repeat 2 more times for different targets and ranges. But both of those methods rely on knowing WHAT you're looking at. Say you're in a forest and you can't differentiate between trees, but you know where key trees are. These trees have been hand picked as "landmarks." You have a robot moving through that forest slowly. Do you know of any ways to determine location based solely off of angle and range, exploiting geometry between landmarks? Note, you will see other trees as well, so you won't know which trees are key trees. Ignore the fact that a target may be occluded. Our pre-algorithm takes care of that. 1) If this exists, what's it called? I can't find anything. 2) What do you think the odds are of having two identical location 'hits?' I imagine it's fairly rare. 3) If there are two identical location 'hits,' how can I determine my exact location after I move the robot next. (I assume the chances of having 2 occurrences of EXACT angles in a row, after I reposition the robot, would be statistically impossible, barring a forest growing in rows like corn). Would I just calculate the position again and hope for the best? Or would I somehow incorporate my previous position estimate into my next guess? If this exists, I'd like to read about it, and if not, develop it as a side project. I just don't have time to reinvent the wheel right now, nor have the time to implement this from scratch. So if it doesn't exist, I'll have to figure out another way to localize the robot since that's not the aim of this research, if it does, lets hope it's semi-easy.

    Read the article

  • ImageMagick on Mac OSX Snow Leopard. Is there any way to get it to compile and run?

    - by ?????
    It seems that I have more trouble getting standard Unix things to run on Snow Leopard than any other platform--including Windows cygwin For the past couple of days, I've been trying to get ImageMagick to run on Snow Leopard. The most obvious way, Mac Ports, fails: tppllc-Mac-Pro:ImageMagick-sl swirsky$ sudo port install imagemagick ---> Computing dependencies for p5-locale-gettext ---> Configuring p5-locale-gettext Error: Target org.macports.configure returned: configure failure: shell command " cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_perl_p5-locale-gettext/work/gettext-1.05" && /opt/local/bin/perl Makefile.PL INSTALLDIRS=vendor " returned error 2 Command output: checking for gettext... no checking for gettext in -I/opt/local/include -arch i386 -L/opt/local/lib -lintl...gettext function not found. Please install libintl at Makefile.PL line 18. no Error: Unable to upgrade port: 1 Error: Unable to execute port: upgrade xorg-libXt failed Before reporting a bug, first run the command again with the -d flag to get complete output. tppllc-Mac-Pro:ImageMagick-sl swirsky$ Not wanting to spend another two days figuring out why my libintl doesn't have a "gettext" function, I tried a different route: the script mentioned here: http://github.com/masterkain/ImageMagick-sl This script downloads and installs an ImageMagic independently of MacPorts issues tppllc-Mac-Pro:ImageMagick-sl swirsky$ /usr/local/bin/convert dyld: Library not loaded: /opt/local/lib/libiconv.2.dylib Referenced from: /opt/local/lib/libfontconfig.1.dylib Reason: Incompatible library version: libfontconfig.1.dylib requires version 8.0.0 or later, but libiconv.2.dylib provides version 7.0.0 Trace/BPT trap It downloads everything and compiles fine, but fails when I try to run it, with the message above. So now I'm two steps away from ImageMagick, trying to get a newer libiconv on my machine. I downloaded the latest libiconv, compiled and built it. I put the resulting library in /opt/local/lib, and I still get the same error message: tppllc-Mac-Pro:.libs swirsky$ sudo mv libiconv.2.dylib /opt/local/lib/libiconv.2.dylib tppllc-Mac-Pro:.libs swirsky$ convert dyld: Library not loaded: /opt/local/lib/libiconv.2.dylib Referenced from: /opt/local/lib/libfontconfig.1.dylib Reason: Incompatible library version: libfontconfig.1.dylib requires version 8.0.0 or later, but libiconv.2.dylib provides version 7.0.0 Trace/BPT trap Now here's something interesting. The error message shows it's looking in /opt/local/lib/libiconv.2.dylib. otools -L shows that this does implement 8.0.0: tppllc-Mac-Pro:.libs swirsky$ otool -L /opt/local/lib/libiconv.2.dylib /opt/local/lib/libiconv.2.dylib: /usr/local/lib/libiconv.2.dylib (compatibility version 8.0.0, current version 8.0.0) /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.0.0) tppllc-Mac-Pro:.libs swirsky$ And, for good measure, I set the DYLD_LIBRARY_PATH to make sure this directory is the one for dynamic libraries. So even though I do have a library that provides 8.0.0, it's being seen as 7.0.0! Any ideas why this would happen? So here's my question: Is it possible to get ImageMagick to run on OSX Snow Leopard? Are there any binary distributions that have static libraries baked in so I don't have to worry about these issue/

    Read the article

  • Optimize date query for large child tables: GiST or GIN?

    - by Dave Jarvis
    Problem 72 child tables, each having a year index and a station index, are defined as follows: CREATE TABLE climate.measurement_12_013 ( -- Inherited from table climate.measurement_12_013: id bigint NOT NULL DEFAULT nextval('climate.measurement_id_seq'::regclass), -- Inherited from table climate.measurement_12_013: station_id integer NOT NULL, -- Inherited from table climate.measurement_12_013: taken date NOT NULL, -- Inherited from table climate.measurement_12_013: amount numeric(8,2) NOT NULL, -- Inherited from table climate.measurement_12_013: category_id smallint NOT NULL, -- Inherited from table climate.measurement_12_013: flag character varying(1) NOT NULL DEFAULT ' '::character varying, CONSTRAINT measurement_12_013_category_id_check CHECK (category_id = 7), CONSTRAINT measurement_12_013_taken_check CHECK (date_part('month'::text, taken)::integer = 12) ) INHERITS (climate.measurement) CREATE INDEX measurement_12_013_s_idx ON climate.measurement_12_013 USING btree (station_id); CREATE INDEX measurement_12_013_y_idx ON climate.measurement_12_013 USING btree (date_part('year'::text, taken)); (Foreign key constraints to be added later.) The following query runs abysmally slow due to a full table scan: SELECT count(1) AS measurements, avg(m.amount) AS amount FROM climate.measurement m WHERE m.station_id IN ( SELECT s.id FROM climate.station s, climate.city c WHERE -- For one city ... -- c.id = 5182 AND -- Where stations are within an elevation range ... -- s.elevation BETWEEN 0 AND 3000 AND 6371.009 * SQRT( POW(RADIANS(c.latitude_decimal - s.latitude_decimal), 2) + (COS(RADIANS(c.latitude_decimal + s.latitude_decimal) / 2) * POW(RADIANS(c.longitude_decimal - s.longitude_decimal), 2)) ) <= 50 ) AND -- -- Begin extracting the data from the database. -- -- The data before 1900 is shaky; insufficient after 2009. -- extract( YEAR FROM m.taken ) BETWEEN 1900 AND 2009 AND -- Whittled down by category ... -- m.category_id = 1 AND m.taken BETWEEN -- Start date. (extract( YEAR FROM m.taken )||'-01-01')::date AND -- End date. Calculated by checking to see if the end date wraps -- into the next year. If it does, then add 1 to the current year. -- (cast(extract( YEAR FROM m.taken ) + greatest( -1 * sign( (extract( YEAR FROM m.taken )||'-12-31')::date - (extract( YEAR FROM m.taken )||'-01-01')::date ), 0 ) AS text)||'-12-31')::date GROUP BY extract( YEAR FROM m.taken ) The sluggishness comes from this part of the query: m.taken BETWEEN /* Start date. */ (extract( YEAR FROM m.taken )||'-01-01')::date AND /* End date. Calculated by checking to see if the end date wraps into the next year. If it does, then add 1 to the current year. */ (cast(extract( YEAR FROM m.taken ) + greatest( -1 * sign( (extract( YEAR FROM m.taken )||'-12-31')::date - (extract( YEAR FROM m.taken )||'-01-01')::date ), 0 ) AS text)||'-12-31')::date The HashAggregate from the plan shows a cost of 10006220141.11, which is, I suspect, on the astronomically huge side. There is a full table scan on the measurement table (itself having neither data nor indexes) being performed. The table aggregates 237 million rows from its child tables. Question What is the proper way to index the dates to avoid full table scans? Options I have considered: GIN GiST Rewrite the WHERE clause Separate year_taken, month_taken, and day_taken columns to the tables What are your thoughts? Thank you!

    Read the article

  • Can I ensure all tests contain an assertion in test/unit?

    - by Andrew Grimm
    With test/unit, and minitest, is it possible to fail any test that doesn't contain an assertion, or would monkey-patching be required (for example, checking if the assertion count increased after each test was executed)? Background: I shouldn't write unit tests without assertions - at a minimum, I should use assert_nothing_raised if I'm smoke testing to indicate that I'm smoke testing. Usually I write tests that fail first, but I'm writing some regression tests. Alternatively, I could supply an incorrect expected value to see if the test is comparing the expected and actual value.

    Read the article

  • Possible loss of precision; extracting char from string

    - by Troy
    I am getting a string from the user and then doing some checking to make sure it is valid, here is the code I have been using; char digit= userInput.charAt(0) - '0'; This had been working fine until I did some work on another method, I went to compile and have been receiving a 'possible loss of precision' error since then. What am I doing wrong?

    Read the article

  • Delphi - Why does ExplicitWidth and ExplicitHeight keep appearing in .DFM files and what is it!?

    - by Pauk
    We've noticed that when checking in updates that our .DFM files have had ExplicitWidth and ExplicitHeight properties added for what appears to be no particular reason. My two questions are, what are they for and why do they get automatically added by Delphi? Below is an example with the property in: object Splitter2: TcxSplitter Left = 0 Top = 292 Width = 566 Height = 8 Cursor = crVSplit HotZoneClassName = 'TcxXPTaskBarStyle' AlignSplitter = salBottom Control = BottomPanel Color = clBtnFace ExplicitWidth = 8 end

    Read the article

  • How does XmlSiteMapProvider check user to be in specified role?

    - by abatishchev
    I roll my own SiteMapProvider inheriting System.Web.XmlSiteMapProvider. I want to override logic of checking user to be in a role specified in siteMapNode's property roles: <siteMapNode url="Add.aspx?type=user" title="Add user" roles="admin" /> How can I do that? Which class's member does XmlSiteMapProvider call to check that if securityTrimmingEnabled="true"?

    Read the article

  • which is the most secure way to check variables type javascript

    - by mck89
    Hi, i need to check the type of a variable in javascript, i know 3 ways to do it: instanceof operator: if(a instanceof Function) typeof operator: if(typeof a=="function" toString method (jQuery uses this): Object.prototype.toString.call(a) == "[object Function]" Which is the most secure way to do type checking beetween these solutions? and why? Please don't tell me that the last solution is better only because jQuery uses that.

    Read the article

  • Is there any way to delete an HttpOnly cookie from C# Selenium tests?

    - by BenA
    I have a set of C# Selenium tests that need to delete a cookie that has the HttpOnly flag set. Unfortunately the DefaultSelenium.GetCookie() and DefaultSelenium.DeleteCookie() commands aren't able to access the cookie, because it has that HttpOnly flag set. I've confirmed this by removing the flag by hand, and checking that subsequent calls to either of those methods are then happily able to manipulate the cookie in question. Is there any other way to do this via the Selenium .NET client driver? All ideas welcome!

    Read the article

  • Javascript: how to tell if a node object has been inserted into a document yet

    - by thomasrutter
    I'd like to be able to identify whether a given DOM node has been inserted into a document, or part of one, yet, or whether it is fresh out of document.createElement() or similar and has not been placed anywhere. In most browsers just checking the parentNode works. if (!node.parentNode) { // this node is not part of a larger document } However, in Internet Explorer it appears that new elements, even right after they've been created with document.createElement() already have a parentNode object (of type DispHTMLDocument??). Any other nice cross-browser and reliable way?

    Read the article

  • which is the most accurate way to check variables type javascript

    - by mck89
    Hi, i need to check the type of a variable in javascript, i know 3 ways to do it: instanceof operator: if(a instanceof Function) typeof operator: if(typeof a=="function" toString method (jQuery uses this): Object.prototype.toString.call(a) == "[object Function]" Which is the most accurate way to do type checking beetween these solutions? and why? Please don't tell me that the last solution is better only because jQuery uses that.

    Read the article

  • NoMethodError: undefined method `has_attached_file'

    - by mirza
    Paperclip produces this error, after checking out the plugin's rails3 branch. My Gemfile has following line: gem 'paperclip', :git => 'http://github.com/thoughtbot/paperclip.git', :branch => 'rails3' And the error message is: NoMethodError: undefined method `has_attached_file' for #<Class:0x2a50530>

    Read the article

  • Check for a string format...

    - by ThePower
    I need an simple way to check whether a string that is sent to my function is of the form: (x + n)(x + m) //the +'s can be minus' //n and m represent a double //x represents the char 'x' Is there a simple string format that I can use to check that this is the form. As opposed to checking each character singularly. The whitespace will be removed to save any confusion. Regards Lloyd

    Read the article

  • how to handle this type of things. using asp.net mvc

    - by kumar
    hello friends, i have public jsonresult update(studentinfo s) { for(i=0;i>0;i++) { var x = // i am getting some x so i am checking again if( x != null) { var updateuser = student.update(s.student,"",""); **return json(updateuser.ToString());** // if i keep it here i am getting exceptoin saying not all code paths return value bec this return i can not keep it out for loop bec each and evary updateuser i need to return json.. } } } how to overcome this type of things? thanks

    Read the article

  • Nginx syntax problem '~*'

    - by Joseph Silvashy
    I have at condition checking to see if user has a cookie like this: if ($http_cookie ~* "developer=true" ) { ... } I'm not familiar with the ~* syntax, I assume that that means if it 'contains', but what about the opposite? like what if I wanted to check if $http_cookie doesn't contain that cookie?

    Read the article

  • SQL Query to find duplicates not returning any results

    - by TheDudeAbides
    I know there are duplicate account numbers in this table, but this query returns no results. SELECT [CARD NUMBER],[CUSTOMER NAME],[ACCT NBR 1],[ACCT NBR 2], COUNT([ACCT NBR 1]) AS NumOccurences FROM DebitCardData.dbo.['ATM Checking Accts - Active$'] GROUP BY [CARD NUMBER],[CUSTOMER NAME],[ACCT NBR 1],[ACCT NBR 2] HAVING (COUNT([ACCT NBR 1])1)

    Read the article

  • How could I get an .ear's filesize at runtime?

    - by adam
    I started out attempting to do this with the Length ant task, but realized that that would be done before the ear is packaged. Packaging the ear, then checking the file size, and then placing it in the ear would effect the size of the ear. Is there a way to get the ear's size programmatically at run-time? Or perhaps an MBean that would have that information?

    Read the article

  • How to safely use VSS when using a working directory on a thumb drive?

    - by MatthewMartin
    I know putting code into VSS in general is as safe as putting money into a mutual fund run by Bernard Madoff, but I don't have the luxury of ditching it for subversion. That said, I need to be able to write code on two machines, I'm considering checking out code to a flash thumb drive. Anyone know in advance what I should/shouldn't do to avoid loss of work? Do I need to ensure the drive letter stays the same?

    Read the article

  • Is there a good way of displaying required field indicators when using DataAnnotations in MVC 2?

    - by Jeremy Gruenwald
    I've got validation working with DataAnnotations on all my models, but I'd like to display an indicator for required fields on page load. Since I've got all my validation centralized, I'd rather not hard-code indicators in the View. Calling validation on load would show the validation summary. Has anyone found a good way of letting the model determine what's required, but checking it upon rendering the view, similar to Html.ValidationMessageFor?

    Read the article

  • Is DateTime.ParseExact() faster than DateTime.Parse()

    - by Nassign
    I would like to know if ParseExact is faster than Parse. I think that it should be ParseExact since you already gave the format but I also think all the checking for the Culture info would slow it down. Does microsoft say in any document on performance difference between the two. The format to be used is a generic 'yyyy/MM/dd' format .

    Read the article

< Previous Page | 62 63 64 65 66 67 68 69 70 71 72 73  | Next Page >