Generate QR Code PNG Image and Sharing with Platform Specific Channel. When user taps on the sharing button we invoke the _captureAndSharePng function that will get the RepaintBoundary object with ...With dynamic QR Codes, the same QR Code can be used to display a different campaign every day. Where can you place the QR Codes? QR Codes can be placed on the product itself, the box it comes in or the crate it was shipped in. Make sure it is scannable by ensuring it is at least 2 cm x 2 cm in size.Dynamic Qr Codes also give you statistics of how many people scanned your QR Codes, from where and on what date. This QR Code type is most used by business owners (restaurants, gyms, clothing stores, etc.), artists, influencers, and non-developers users. Dynamic QR Codes; Customized Colors & Shapes for QR Codes; QR Code StatisticsLearn how to make a QR code for various purposes, such as websites, forms, or phone calls, using online generators or Chrome. Find out how to optimize …1. QR Code advertising examples: Taco Bell makes QR Codes edible. Taco Bell has been incorporating QR Codes as part of its promotional campaigns for quite a …A QR code can be generated from a series of segments having different encoding modes to optimize the data compression. However, switching from a mode to another has a cost which may lead to a worst result if it's not taken into account. See Manual mode for an example of how to specify segments with different encoding modes. Auto mode With dynamic QR Codes, the same QR Code can be used to display a different campaign every day. Where can you place the QR Codes? QR Codes can be placed on the product itself, the box it comes in or the crate it was shipped in. Make sure it is scannable by ensuring it is at least 2 cm x 2 cm in size. A QR code menu example. In the QR code, the arrangement of the squares—or data modules, as they’re called—is actually our URL. It’s just been translated from the alphanumeric string of the URL into a collection …For example, a gym could include a QR code on a member’s monthly invoice. The member would simply scan the code to process the payment, instead of needing to go through the manual process each time. Event ticketing For events like concerts and sporting games, organizers can embed a QR code on the ticket. This can serve both as a proof of ...Find & Download Free Graphic Resources for Sample Qr Code. 99,000+ Vectors, Stock Photos & PSD files. Free for commercial use High Quality ImagesDetect and read QR codes from an image. The following image is used as an example. The text stored in each QR Code is, from left to right, QR Code One, QR Code Two, and QR Code Three. The rightmost QR Code is masked with a white square in the center to make it difficult to read.1. Rayleigh Quotient. The Rayleigh quotient of x ∈ Rm: xT Ax r(x) = xT x. For an eigenvector x, the corresponding eigenvalue is r(x) = λ. For general x, r(x) = α that …1. Directing Customers to a Landing Page or Website. 2. A Quick Way to Download an App. 3. An Easy Way to Pass on Your Business Details. 4. Use a QR … A simple QR code example might include encoding text, a URL, or contact information. For instance, a business card with a QR code linking to a professional profile or website exemplifies the efficiency of QR codes in sharing information. This extends to creative implementations like incorporating a business card to QR code, allowing seamless ... For example, say you are using an App Store QR Code to drive app downloads. And this campaign has been quite successful. So, you have decided to use this QR Code for another campaign to, say, promote a specific product within your app. Here, a dynamic QR Code will allow you to change the App Store QR Code to App Deep Link …These samples demonstrate how to build apps for the different classes of digital eyewear devices. The Unity samples for HoloLens 2 and Magic Leap 2 show how to attach an AR experience to an Images, Model Targets and VuMarks. The Vuzix M400 and RealWear HMT-1 is supported similar to any Android device with the samples in the Core Features …QR Code, a type of bar code that consists of a printed square pattern of small black and white squares that encode data which can be scanned into a computer system. The black and white squares can represent numbers from 0 to 9, letters from A to Z, or characters in non-Latin scripts such as Japanese kanji.. QR Codes were developed …Open Chrome and navigate to the web page you want to link to with your QR code. Click the Share icon in the URL bar (it looks like a square with an upward-facing arrow). You'll see a QR code icon and the words Create QR Code on the right side. Click on it. Chrome will generate a QR code, ready for you to save and share. Create QR codes to highlight different categories or types of content - videos, campaigns, landing pages, brochures, examples of your work, and feedback pages. For another option, add a download link in a QR code to a PDF version of your flyer or brochure. Adobe Express templates help you stand out on any channel and every device. QR code murals appeared in cities across the world such as Melbourne, Paris, Chicago and London. Each QR code revealed a singular letter, which Swifties pieced …ForQRCode.com offer QR codes in high resolutions, the QR code is generated in either raster vector graphic formats SVG and EPS can be downloaded for free and without registration. ForQRCode is a free QR Code Generator to make your personal QR Code with with your logo, color and esign. Download as PNG, SVG, PDF, and EPS.Feb 12, 2024 · A. Types of QR Code format. QR Codes come in multiple formats. First, we have the common QR Code Models 1 and 2, often used for URLs, PDFs, image galleries, vCards, and Google Maps QR Codes. Then, there’s the Micro QR Code. It’s smaller than a regular QR Code, perfect for small product packaging where space is limited. How do I create a WiFi QR Code? Enter the name of the WiFi network in the network name field. Make sure it matches the name on your router exactly. If this is a hidden network, tick the ‘Hidden’ box next to the field. Enter the WiFi password (case sensitive) and select the security protocol you’ve chosen for your network. Create QR codes to highlight different categories or types of content - videos, campaigns, landing pages, brochures, examples of your work, and feedback pages. For another option, add a download link in a QR code to a PDF version of your flyer or brochure. Adobe Express templates help you stand out on any channel and every device. A vCard QR Code contains all the information of the vCard, and put them in a QR Code format, which can be scanned using your phone’s camera to import and save the contact details. ... A use case for vCard QR Codes would be for example a business card. You can hand them out to your clients, and they can instantly add your contact details by ...4 QR Factorization 4.1 Reduced vs. Full QR Consider A ∈ Cm×n with m ≥ n. The reduced QR factorization of A is of the form A = QˆR,ˆ where Qˆ ∈ Cm×n with orthonormal columns and Rˆ ∈ Cn×n an upper triangular matrix such that Rˆ(j,j) 6= 0, j = 1,...,n. As with the SVD Qˆ provides an orthonormal basis for range(A), i.e., the ...QR codes to ease Johor causeway jam [NSTTV] JOHOR BARU: THE perennial congestion at the Johor-Singapore Causeway — acknowledged as the world's busiest …How to scan QR codes on Android. Step 1:From your Android device, open the camera app. Again, ensure the rear-facing camera is selected. Step 2:Point your camera at the QR code. Center the box over the code to scan it. Step 3:Tap on the URL popup banner to connect directly to the intended destination. Here are a few of the most memorable examples of QR codes – and a few tips for putting this strategy to work for your brand. 1. Creative Ads for Apps. Here’s an eyecatching way to use a QR code in an ad by Burger King at the VMAs. The QR code was included in a video ad several times and took users to link to download the burger king app. Jul 29, 2022 · Right-click on the page. Select “Create QR Code for this Page”. Download the QR code. You’ll notice the QR code has a dinosaur in the middle of the interior. If you’re using the code for marketing materials, this method might not work best, but if you need the code for quick, simple access, it can work perfectly. QR codes are commonly used for holding data such as: The truth is that you can store lots of types of information in a QR code and it all depends only on your imagination. For example, you could also use a QR code to point someone to your Facebook page, or you could use it to display a poem you wrote. With dynamic QR Codes, the same QR Code can be used to display a different campaign every day. Where can you place the QR Codes? QR Codes can be placed on the product itself, the box it comes in or the crate it was shipped in. Make sure it is scannable by ensuring it is at least 2 cm x 2 cm in size. For example: If you have an App in the Apple and Google Play Store you need just one QR Code. ... QR Codes are created using a QR Code generator that encodes the information for a QR Code reader. The QR Codes can then be read with almost any smartphone that has an integrated camera.Detect and read QR codes from an image. The following image is used as an example. The text stored in each QR Code is, from left to right, QR Code One, QR Code Two, and QR Code Three. The rightmost QR Code is masked with a white square in the center to make it difficult to read. R = qr(A) returns the upper-triangular R factor of the QR decomposition A =. Q*R. example. [Q,R] = qr(A) performs a QR decomposition on m -by- n matrix A such that A = Q*R. The factor R is an m -by- n upper-triangular matrix, and the factor Q is an m -by- m orthogonal matrix. example. An example of this is Philippines National Bureau of Investigation (NBI) where NBI clearances now come with a QR code. Many of these applications target mobile-phone users (via mobile tagging ). Users …QR decomposition writteninmatrixform: A = QR ,whereA 2 R m n,Q 2 R m n,R 2 R n: a 1 a 2 a n | {z } A = q 1 q 2 q n | {z } Q 2 6 6 4 r 11 r 12 r 1 n 0 r 22 r 2 n 0 0 r nn 3 7 7 5 | {z } R I Q TQ = I ,andR isuppertriangular&invertible I calledQR decomposition (orfactorization)ofA I usually computed using a variation on Gram-Schmidt procedure which is less sensitive …In the sample app, we place the QR scanner within a Stack widget, so we can tell the user what to scan while the QR code scanner is up. Let’s configure our QRView like so: QRView( cameraFacing: CameraFacing.back, // Use the rear camera key: qrKey, // The global key for the scanner onQRViewCreated: _onQRViewCreated, // Function to …QR Space Pins sample Summary. The Space Pins feature of World Locking Tools is combined with QR code scanning to provide automatic snapping of a Unity scene to a physical environment. As the QR codes are physical features, this is an intrinsically shared experience. See also the accompanying video for some visual clarification. Project source ...Create a New Android Application Project. Tip. You may skip project creation and jump directly to the beginning of the example below. Open Eclipse IDE and go to File → New → Project → Android Application Project. Figure 1. Create a new Android project. Specify the name of the application, the project and the package and then click Next ...The best selection of Royalty Free Scan Qr Sample Vector Art, Graphics and Stock Illustrations. Download 240+ Royalty Free Scan Qr Sample Vector Images.Enter your Bitcoin or crypto address in the address field. Make sure it has all 34 characters. Specify the amount you’d like to receive. Then add a frame and change the colors of the QR Code to make it stand out. Finally, download your free custom QR Code! Generador de códigos QR - Crea códigos QR gratis. Para permitir el seguimiento, crea un Código QR Dinámico. Generador de Códigos QR Online gratuito para hacer tus propios Códigos QR. Admite códigos dinámicos, seguimiento, análisis, texto libre, vCards y mucho más. First import QRCoder via using -statement. using QRCoder; Then create an instance of the QRCodeGenerator -class and call the CreateQrCode -method with the payload (text) you want to encode into the QR Code. QRCodeGenerator qrGenerator = new QRCodeGenerator (); QRCodeData qrCodeData = qrGenerator.CreateQrCode("The …EPC QR code. The European Payments Council Quick Response Code guidelines define the content of a QR code that can be used to initiate SEPA credit transfer (SCT). It contains all the necessary information in clear text. These QR code guidelines are used on many invoices and payment requests in the countries that support it (Austria, Belgium ...A QR code generator is a software which stores data into a QR code (for example a text or a website address). E.g. this can be easily done with our online QR generator goQR.me: just create a QR code by typing in your data and download it as high resolution PNG or vector graphic (SVG, EPS). Now you may print your free QR code or embed it on your ... of the matrix into an orthogonal matrix and a triangular matrix. A QR decomposition of a real square matrix A is a decomposition of A as A = QR; where Q is an orthogonal matrix (i.e. QTQ = I) and R is an upper triangular matrix. If A is nonsingular, then this factorization is unique. There are several methods for actually computing the QR ... Creating a QR Code step by step. This JavaScript demo application visualizes in detailed steps, how a text string is encoded into a QR Code barcode symbol. The content of this …Jan 23, 2024 · Here are some creative ways individuals and businesses can use QR codes. 1. Bus Stops and Train Stations. QR codes are being used in bus stops and train stations in cities worldwide. In London, for example, Transport for London has placed QR codes at bus stops so that people can scan the code and get information about the bus route and schedule ... Create QR codes to highlight different categories or types of content - videos, campaigns, landing pages, brochures, examples of your work, and feedback pages. For another option, add a download link in a QR code to a PDF version of your flyer or brochure. Adobe Express templates help you stand out on any channel and every device. Here are a few of the most memorable examples of QR codes – and a few tips for putting this strategy to work for your brand. 1. Creative Ads for Apps. Here’s an eyecatching way to use a QR code in an ad by Burger King at the VMAs. The QR code was included in a video ad several times and took users to link to download the burger king app. An AR Code is a type of barcode that contains the necessary information to generate an Augmented Reality 3D experience. It operates without the need for a dedicated app on smartphones and AR/VR headsets like the Apple Vision Pro. Begin creating, managing, and tracking your AR experiences.An example of QR Code campaign tracking with QR Code Generator PRO. Seamless connection between print and digital. Contrary to common belief, print advertising isn’t dead. Print marketing tools like flyers, brochures, and business cards still contribute to the success of marketing campaigns because they create tactile connections and build ...Simple Qr code : Add a route and return QR code. Simply add the following code in your web.php file. Route::get('qrcode', function {return QrCode::size(300)->generate('A basic example of QR code!');}); size() function is used to specify the size of QR. When you hit the route /QRcode, you get the QR code as below : QR Code with …Pro Mode - if you want to implement your own user interface . You can use Html5Qrcode class to set up your QR code scanner (with your own user interface) and allow users to scan QR codes using the camera or by choosing an image file in the file system or native cameras in smartphones.. You can use the following APIs to fetch camera, start …Generally, you are required to provide details of the DuitNow QR payment made such as date, time, amount and receipt or reference number of the payment. Additionally, you may also be asked to provide details of the Merchant such as store name, location, reason for the dispute or request for refund and/or and any other information as deemed ...Find React Qr Scanner Examples and Templates. Use this online react-qr-scanner playground to view and fork react-qr-scanner example apps and templates on CodeSandbox. Click any example below to run it instantly or find templates that can be used as a pre-built solution! react React example starter project. react-qr-reader4.https://faculty.washington.edu/kutz/am584/am584.htmlThis lecture focuses builds on the classic QR decomposition and introduces the concept of Householder ref...He said that the overall plan is to “widen the scope of travellers” who will be able to use the QR code system. Following Singapore’s roll out of its QR code system in …The best selection of Royalty Free Scan Qr Sample Vector Art, Graphics and Stock Illustrations. Download 240+ Royalty Free Scan Qr Sample Vector Images.We would like to show you a description here but the site won’t allow us.EPC QR code. The European Payments Council Quick Response Code guidelines define the content of a QR code that can be used to initiate SEPA credit transfer (SCT). It contains all the necessary information in clear text. These QR code guidelines are used on many invoices and payment requests in the countries that support it (Austria, Belgium ...With dynamic QR Codes, the same QR Code can be used to display a different campaign every day. Where can you place the QR Codes? QR Codes can be placed on the product itself, the box it comes in or the crate it was shipped in. Make sure it is scannable by ensuring it is at least 2 cm x 2 cm in size.Example Generating AIM QR-Code with FNC1 in Second Position. When generating AIM QR-Code symbols, the first AI is required directly after the ~2 in parentheses. The parentheses will not be encoded and are only used to encode the first AI within the symbol. If additional FNC1s need to be encoded, they should be encoded as ~2 in any mode.QR code scanner that can be embedded inside flutter. It uses zxing in Android and MTBBarcode scanner in iOS. Homepage Repository (GitHub) View/report issues. Documentation. API reference. License. BSD-2-Clause . Dependencies. flutter, flutter_web_plugins, js. More. Packages that depend on qr_code_scannerExample, <key>NSCameraUsageDescription</key> <string>This app needs camera access to scan QR codes</string> <key>NSPhotoLibraryUsageDescription</key> <string>This app needs photos access to get QR code from photo library</string> macOS # Ensure that you granted camera permission in XCode -> Signing & Capabilities: Web #QR Code Explained. QR is a two-dimensional or matrix code that can encode up to 4,000 characters or 7,000 digits. The code is easily recognized by the characteristic three finder patterns in the corners of the symbol: Those patterns are quite large, so the code needs more space than other 2D symbologies, at least with small amounts of data.QR Code Generator. ‘QR Code Generator’ helps you to quickly create a Vector QR code. Just enter your content or URL then click ‘Place QR code’ — or CMD/Control + Enter. This is also great for creating a QR code to share the Figma file link – or a link to your prorotype. Tip: On iOS – the built in camera app can scan QR codes. In order to create a QR Code, select the QR Code type. Without registration, you can use several types of Codes. For example, apply a vCard QR Code to save your contact information or a URL QR Code to link to a Web page. It is also possible to encode email or text messages in a QR Code. First import QRCoder via using -statement. using QRCoder; Then create an instance of the QRCodeGenerator -class and call the CreateQrCode -method with the payload (text) you want to encode into the QR Code. QRCodeGenerator qrGenerator = new QRCodeGenerator (); QRCodeData qrCodeData = qrGenerator.CreateQrCode("The …Feb 4, 2021 · The QR decomposition of a matrix thus allows to write the matrix in factored form: where is a matrix with , and is ,upper-triangular. Matlab syntax. >> [Q,R] = qr(A,0); % A is a mxn matrix, Q is mxn orthogonal, R is nxn upper triangular. Example: QR decomposition of a 4x6 matrix. Try QRServer API; it provides a simple way to generate QR codes programmatically. You can specify the size, data, and other parameters in the API call. …Creating a QR Code step by step. This JavaScript demo application visualizes in detailed steps, how a text string is encoded into a QR Code barcode symbol. The content of this … QR Code Model 1 and 2: This is the QR Code we see on a daily basis. More than 30+ different types of QR codes can be created for business or personal use. Some of these QR Codes are more suited to a particular QR Code use case, whereas some can help your QR Code marketing endeavors. Some of the most common types of QR Codes include: URL QR Code. 2. I'm using Zebra ZPLII to create a label with a QR code to open an specific url. When I use iPhone camera to scan the QR phone shows "unusable data" and when I try with an external QR reader the text extracted from the QR is not the same from the label. For example if I write www.google.com the string that I have from reading the QR is ...11/18/2022. QR Code Examples - How to use QR Codes skillfully. QR Codes to movie trailers. QR Codes for App Download. QR Codes on product packaging. QR Codes for real estate. QR Codes on business …A QR code menu example. In the QR code, the arrangement of the squares—or data modules, as they’re called—is actually our URL. It’s just been translated from the alphanumeric string of the URL into a collection …2. I'm using Zebra ZPLII to create a label with a QR code to open an specific url. When I use iPhone camera to scan the QR phone shows "unusable data" and when I try with an external QR reader the text extracted from the QR is not the same from the label. For example if I write www.google.com the string that I have from reading the QR is ...QR Ultra NEW! Our newest QR menu creator is superfast for your customers – menu updates appear on their phones without requiring a refresh! Change the QR code design itself with colors, your logo and more. Add a business photo, store info, your logo, and additional menus – all from the same QR code page. Use QR codes at multiple …QR code scanner that can be embedded inside flutter. It uses zxing in Android and MTBBarcode scanner in iOS. Homepage Repository (GitHub) View/report issues. Documentation. API reference. License. BSD-2-Clause . Dependencies. flutter, flutter_web_plugins, js. More. Packages that depend on qr_code_scannerA QR code. That QR codes encode and provide information along two axes (up-and-down and side-to-side) has numerous benefits. Speed is one of the most impactful; in fact, QR codes were invented in 1994 primarily to increase scanning speed. See our QR code vs barcode post for more information between the two.Apr 4, 2024 · 4. QR Code link example: L’Oreal engages customers on the go with QR Codes. Another example of brands using QR Codes is when L’Oreal partnered with Glamour and used QR Codes inside taxis to capture customers stuck in traffic. The campaign promoted the range of Lancôme and Yves Saint Laurent product lines by linking QR Code campaigns to ... This fact, combined with the factorization theorem in this section, provides a useful way to simplify many matrix calculations (for example, in least squares approximation). QR-factorization025100 Let A be an m × n matrix with independent columns. A QR-factorization1 of A expresses it as A = QR where Q is m × n with orthonormal columns and R ... The method above generates a QR code with some data. Next, we pass the QR code to the modifiedQRcode () method to add text to the top and bottom of the generated QR code. The modifiedQRcode () method replicates the QR code and modifies it: int matrixWidth = matrix.getWidth(); int matrixHeight = matrix.getHeight();These samples demonstrate how to build apps for the different classes of digital eyewear devices. The Unity samples for HoloLens 2 and Magic Leap 2 show how to attach an AR experience to an Images, Model Targets and VuMarks. The Vuzix M400 and RealWear HMT-1 is supported similar to any Android device with the samples in the Core Features …While initial testing of 30 samples passed a validity test, it would take another year and more than 200 samples to obtain statistically significant results, …QR Space Pins sample Summary. The Space Pins feature of World Locking Tools is combined with QR code scanning to provide automatic snapping of a Unity scene to a physical environment. As the QR codes are physical features, this is an intrinsically shared experience. See also the accompanying video for some visual clarification. Project source ... QR Code Scanner. is a handy application for scanning a QR code with a smartphone. Create codes with our free QR generator of codes. Comprehensible interface, variety in choosing the type of your QR-code, the ability to view statistics! Easy QR code maker. Create QR code in two clicks: 👉 upload your link, 👉 generate QR and 👍 download it!
Create a New Android Application Project. Tip. You may skip project creation and jump directly to the beginning of the example below. Open Eclipse IDE and go to File → New → Project → Android Application Project. Figure 1. Create a new Android project. Specify the name of the application, the project and the package and then click Next .... Niagara choice
For example, a gym could include a QR code on a member’s monthly invoice. The member would simply scan the code to process the payment, instead of needing to go through the manual process each time. Event ticketing For events like concerts and sporting games, organizers can embed a QR code on the ticket. This can serve both as a proof of ...Example Generating AIM QR-Code with FNC1 in Second Position. When generating AIM QR-Code symbols, the first AI is required directly after the ~2 in parentheses. The parentheses will not be encoded and are only used to encode the first AI within the symbol. If additional FNC1s need to be encoded, they should be encoded as ~2 in any mode.2. I'm using Zebra ZPLII to create a label with a QR code to open an specific url. When I use iPhone camera to scan the QR phone shows "unusable data" and when I try with an external QR reader the text extracted from the QR is not the same from the label. For example if I write www.google.com the string that I have from reading the QR is ...Dynamic QR Codes Explained. With Dynamic Qr Codes you can create a customized landing page for your QR Code that can be changed and updated whenever you want no matter if the QR Code is created or even if it went public. Dynamic Qr Codes also give you statistics of how many people scanned your QR Codes, from where and on what date.Pro Mode - if you want to implement your own user interface . You can use Html5Qrcode class to set up your QR code scanner (with your own user interface) and allow users to scan QR codes using the camera or by choosing an image file in the file system or native cameras in smartphones.. You can use the following APIs to fetch camera, start … Here are a few of the most memorable examples of QR codes – and a few tips for putting this strategy to work for your brand. 1. Creative Ads for Apps. Here’s an eyecatching way to use a QR code in an ad by Burger King at the VMAs. The QR code was included in a video ad several times and took users to link to download the burger king app. A QR code. That QR codes encode and provide information along two axes (up-and-down and side-to-side) has numerous benefits. Speed is one of the most impactful; in fact, QR codes were invented in 1994 primarily to increase scanning speed. See our QR code vs barcode post for more information between the two.chillerlan/php-qrcode. A PHP QR Code generator based on the implementation by Kazuhiko Arase, namespaced, cleaned up, improved and other stuff. It also features a QR Code reader based on a PHP port of the ZXing library. Attention: there is now also a javascript port: chillerlan/js-qrcode.A QR code menu example. In the QR code, the arrangement of the squares—or data modules, as they’re called—is actually our URL. It’s just been translated from the alphanumeric string of the URL into a collection … This fact, combined with the factorization theorem in this section, provides a useful way to simplify many matrix calculations (for example, in least squares approximation). QR-factorization025100 Let A be an m × n matrix with independent columns. A QR-factorization1 of A expresses it as A = QR where Q is m × n with orthonormal columns and R ... May 30, 2022 · This page titled 3.8: QR Factorization is shared under a CC BY 3.0 license and was authored, remixed, and/or curated by Jeffrey R. Chasnov via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request. Creating a QR Code step by step. This JavaScript demo application visualizes in detailed steps, how a text string is encoded into a QR Code barcode symbol. The content of this …orthogonal, for example at the first step: ... • Compute the factor R of a QR factorization of m × n matrix A (m ≥ n) • Leave result in place of A, store reflection vectors vk for later use Algorithm: Householder QR Factorization for k = 1 to n . x = A. k:m,k v. k = sign(x 1 QR algorithm. In numerical linear algebra, the QR algorithm or QR iteration is an eigenvalue algorithm: that is, a procedure to calculate the eigenvalues and eigenvectors of a matrix. The QR algorithm was developed in the late 1950s by John G. F. Francis and by Vera N. Kublanovskaya, working independently. .