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How to Merge and Split PDF Files Online for Free (100% Safe & No Uploads!)

  PDF MERGE & SPLIT   Ever wanted to join two or more PDF files into one? Or maybe you have a big 50-page document and only need pages 5 to 10? Most online websites ask you to upload your personal files to their servers. This can be slow, and you might worry about your private information. Today, we will show you an easy, free, and completely safe way to combine and split your PDFs directly inside your web browser using Local PDF Tools . Why Use Local PDF Tools? Your Files Never Leave Your Device : Your documents are processed directly on your computer or phone. Nothing is sent to any external server. 100% Free with No Limits : You do not need to create an account, sign in, or pay any subscription fees. Super Fast : Because you don’t have to wait for large files to upload, everything happens in seconds. How to Merge Multiple PDFs into One File Merging files means joining them together into a single document: Go to pdfms.senaskat.com .Click on the upload box or drag your PD...

How to Black Out Sensitive Info and Blur Faces in a PDF for Free (No Sign-Up!)

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SafeShield PDF Redact   🔒 Send Documents Without Worry Sometimes you must email your ID, tax form, or bank paper. But you don’t want to share private details like your SSN, home address, or photo. Many people draw a black box with paint tools. That looks safe, but it is not. The hidden text can still be copied. ✅ Use SafeShield Redact — a free tool that makes your files safe in seconds. pdfredact.senaskat.com Why SafeShield Redact is Safer Your files stay on your computer – nothing is uploaded online. 1‑Click Finder – it can spot SSNs, emails, and phone numbers for you. Hide photos & faces – blur a passport photo, signature, or logo with one click. Completely free – no login, no payment, no watermark. 4 Easy Steps Go to pdfredact.senaskat.com and drag your PDF in. Click PII Presets to auto‑find SSNs and emails, or type words you want to remove. To hide a photo or signature, click the Image icon and move the blur shape. Click Redact Selected , then Download your safe P...

Take the Test on ProQuiz!

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Are You as Good a Programmer as You Think?  As developers, we spend hours writing code, reading documentation, and building software. But how often do we actually test our core foundational knowledge? Whether you are preparing for technical interviews, learning a new language, or just want to prove your expertise, taking structured coding tests is one of the fastest ways to find your knowledge gaps. If you are ready to test your programming skills, I highly recommend checking out ProQuiz . Why Take a Coding Test on ProQuiz? 🎯 Validate Your Knowledge: Move past "tutorial hell." Writing code is great, but answering conceptual and syntax-based questions tests your deep understanding. ⚡ Brushing Up for Interviews: The site features quick, targeted tests on syntax, memory management, OOP principles, and structure. Perfect for a pre-interview warmup! 🚀 Five Essential Languages: Challenge yourself in C, C++, Java, Kotlin, or Python . 🆓 Instant & Fricti...

Inverse Matrix by LU Decomposition

One of the application of LU matrix decomposition finds inverse of a square matrix,A. A A -1 = I The square matrix (coefficient matrix) A decomposed into LU (lower triangular and upper triangular) matrix by elementary-row-operations . A = LU after that, inverse matrix A -1 is found by applying forward and back substitution on each column of identity matrix, I and place returning solution vectors x to column of A -1 matrix. Algorithm steps for Matrix Inverse by LU Decomposition Input : a square matrix , A Output : a square matrix, A -1 read matrix A [L,U]= LUDecompose (A) [nrow,ncol]=size(A) I = Identity-matrix(nrow,ncol); iA = zero-matrix(nrow,ncol); For c =1 to ncol Y = forward-substitute (L,I(c)) X = back-substitute (U,Y) A -1 (c,:) = X // set vector X to column of A -1 ...

Solve System of Linear Equations by LU Decompose

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One of the application of LU matrix decomposition is solving system of linear equations. Ax = b A - coefficient matrix b - non-homogeneous vector x - unknown vector (solution vector) The square matrix (coefficient matrix) A decomposed into LU (lower triangular and upper triangular) matrix by elementary-row-operations. A = LU the solution vector X of system found by forward and back substitution. y = forward-substitute L and b X = back-substitute U and y The two or more system of equations have same coefficient matrix A but have different non-homogeneous vectors (b1 ,b2,..), the solutions vectors (x1,x2,..) obtained by once applying LU decomposition over matrix A. System 1 &nbsp&nbsp Ax = b1 ...

Matrix Forward and Back Substitution

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A square matrix is transformed into a Lower triangular matrix L or an Upper triangular matrix U by applying elementary row operation (Gaussian elimination) for solving system linear of equations. A solution vector X of system of linear equations is obtained by applying substitution method. The forward substitution method is applied to matrix L The back substitution method is applied to matrix U Algorithm steps for forward substitution to matrix L Input : a square matrix, A a non-homogeneous vector b Output : Solution vector, X read matrix A read vector b L = transform_to_L (A,b) X = substitute-forward(L); Example of forward substitution to matrix L substitute unknown variables top to bottom approach 0.4286x = 1.7143 3.6667x + 2.3334y = 10.0 2.0x+ + 4.0y + 6.0z = 18.0 find x, from equation 1 ...

Matrix A = LU Decompose

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LU decompose - a square matrix A that can be expressed as product of L and U matrix, is called LU decomposition. A = LU Matrix L - It is called Lower triangular Matrix , whose elements above the main diagonal is zero valued elements. Matrix U - It is called Upper Triangular Matrix , whose elements below the main diagonal is zero valued elements. How to LU decompose - a square matrix A is decomposed or factorized into L and U matrix by elementary row operation , such as swapping two rows and adding or subtracting row by a scalar value. Application of LU decompose It is useful to find solution of system of linear equation and matrix inverse. Algorithm steps for A= LU decompose Read matrix A U = copy (A) L = Identity-matrix() i,j - position of a element in the matrix For i=1 To N Eor j=i+1 To N lambda=U ji /U ii R j <- R j - lambda ...