Singular Value Decomposition (SVD) tutorial. Singular Value Decomposition (SVD) tutorial Singular value decomposition takes a rectangular matrix of gene expression data (defined as A, where A is a n x p matrix) in which the n rows represents the genes, and the p columns represents the experimental conditions. The SVD theorem states: Anxp= Unxn Snxp VTpxp Where UTU = Inxn VTV = Ipxp (i.e. Where the columns of U are the left singular vectors (gene coefficient vectors); S (the same dimensions as A) has singular values and is diagonal (mode amplitudes); and VT has rows that are the right singular vectors (expression level vectors). Calculating the SVD consists of finding the eigenvalues and eigenvectors of AAT and ATA.
To understand how to solve for SVD, let’s take the example of the matrix that was provided in Kuruvilla et al: In this example the matrix is a 4x2 matrix. W x = l x For some scalar l. So to find the eigenvalues of the above entity we compute matrices AAT and ATA. Since W x = l x then (W- lI) x = 0 19.883 x1 + 14 x2 = 0 x3 = 0. FFmpeg codec howto - MultimediaWiki. This page is meant as an introduction to the internal codec API in FFmpeg. It will also show how the codecs are connected with the demuxers. This is by no means a complete guide but enough to understand how to add a codec to FFmpeg. Cook is used as an example throughout. registering the codec libavcodec/avcodec.h The first thing to look at is the AVCodec struct. Here we can see that we have some elements to name the codec, what type it is (audio/video), the supported pixel formats and some function pointers for init/encode/decode and close. Libavcodec/cook.c If we look in this file at the bottom we can see this code: AVCodec cook_decoder = { .name = "cook", .type = CODEC_TYPE_AUDIO, .id = CODEC_ID_COOK, .priv_data_size = sizeof(COOKContext), .init = cook_decode_init, .close = cook_decode_close, .decode = cook_decode_frame, }; First we get an AVCodec struct named cook_decoder.
Here we will find the CodecID enumeration. enum CodecID { ... CODEC_ID_COOK is there in the list. ... ... Codec code. Ffmpeg tutorial. TECH BITS AND PIECES. Free Science and Video Lectures Online!