wgblas
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    Function ssyr

    • Performs the symmetric rank-1 update A = alpha * x * x^T + A

      A is an n×n symmetric matrix stored in row-major order, updated in place. Only the triangle specified by uplo is referenced and updated; the other triangle is left untouched (implied by symmetry).

      import { init, cleanup } from "wgblas";
      import { ssyr } from "wgblas/ssyr";
      import { randomFloat32Array } from "wgblas/random";

      // Reshapes a flat row-major array into rows for console.table's 2D grid view.
      function toMatrix(A, rows, cols, lda = cols) {
        const out = [];
        for (let r = 0; r < rows; r++)
          out.push(Array.from(A.subarray(r * lda, r * lda + cols), (v) => +v.toFixed(4)));
        return out;
      }

      const device = await init();

      // 4×4 symmetric rank-1 update, lower triangle stored; lda = n
      const n = 4, lda = n;
      const alpha = 1.0;
      const x = randomFloat32Array(n, -10, 10);
      const A = randomFloat32Array(n * lda, -10, 10); // only lower triangle is read/updated

      console.log("x:", x);
      console.log("A (lower triangle, before):");
      console.table(toMatrix(A, n, n, lda));
      const { A: result } = await ssyr(device, "lower", n, alpha, x, 1, A, lda, "row-major");
      console.log("A (lower triangle, after):");
      console.table(toMatrix(result, n, n, lda));
      if (typeof process !== "undefined") cleanup();

      Browser (standalone HTML):

      <!doctype html>
      <html lang="en">
        <head>
          <meta charset="UTF-8" />
          <title>ssyr — wgblas browser example</title>
          <script src="https://unpkg.com/wgblas/dist/wgblas.browser.js"></script>
        </head>
        <body>
          <pre id="out">Running…</pre>
          <script>
            const { init, ssyr, randomFloat32Array, cleanup } = window.wgblas;

            // Reshapes a flat row-major array into a newline-per-row grid for display.
            function matrixText(A, rows, cols, lda) {
              const lines = [];
              for (let r = 0; r < rows; r++) {
                const row = [];
                for (let c = 0; c < cols; c++) row.push(A[r * lda + c].toFixed(4));
                lines.push(row.join(", "));
              }
              return lines.join("\n");
            }

            (async () => {
              const device = await init();

              const n = 4, lda = n;
              const alpha = 1.0;
              const x = randomFloat32Array(n, -10, 10);
              const A = randomFloat32Array(n * lda, -10, 10); // only lower triangle is read/updated

              const { A: result } = await ssyr(device, "lower", n, alpha, x, 1, A, lda, "row-major");

              document.getElementById("out").textContent =
                "x: " + Array.from(x).map(v => v.toFixed(4)).join(", ") +
                "\nA (lower triangle, before):\n" + matrixText(A, n, n, lda) +
                "\nA (lower triangle, after):\n" + matrixText(result, n, n, lda);

              cleanup();
            })();
          </script>
        </body>
      </html>

      Parameters

      • device: GPUDevice

        GPUDevice from init()

      • uplo: "lower" | "upper"

        'lower' to use the lower triangle, 'upper' to use the upper triangle

      • n: number

        order of the matrix A (number of rows and columns)

      • alpha: number

        scalar multiplier for x*x^T

      • x: Float32Array

        Float32Array input vector, length at least (n-1)*incx+1

      • incx: number

        stride for x (must be a positive integer)

      • A: Float32Array

        Float32Array, row-major or column-major (see layout), at least (n-1)*lda+n elements

      • lda: number

        leading dimension of A (>= n either way — A is square)

      • Optionallayout: "column-major" | "row-major"

        storage layout of A (default: 'row-major'); for a symmetric matrix, column-major storage just means the other triangle is the one physically referenced for a given uplo

      Returns Promise<{ A: Float32Array; gpuTimeMs?: number }>

      Source code: ssyr.mjs (L15)

    • Performs the symmetric rank-1 update A = alpha * x * x^T + A

      A is kept GPU-resident; x is a CPU Float32Array. A's own layout (set at GpuMatrix.from time) determines the operation — there is no separate layout argument here.

      Parameters

      • device: GPUDevice

        GPUDevice from init()

      • uplo: "lower" | "upper"

        'lower' to use the lower triangle, 'upper' to use the upper triangle

      • n: number

        order of the matrix A

      • alpha: number

        scalar multiplier for x*x^T

      • x: Float32Array

        Float32Array input vector

      • incx: number

        stride for x (must be a positive integer)

      • A: GpuMatrix

        GpuMatrix, GPU-resident

      • lda: number

        leading dimension of A (must equal A.lda)

      Returns Promise<{ gpuTimeMs?: number }>

      Source code: ssyr.mjs (L15)

    • Performs the symmetric rank-1 update A = alpha * x * x^T + A

      x and A are both kept resident on the GPU. A's own layout (set at GpuMatrix.from time) determines the operation — there is no separate layout argument here.

      import { init, cleanup } from "wgblas";
      import { ssyr } from "wgblas/ssyr";
      import { GpuVector } from "wgblas/classes/GpuVector";
      import { GpuMatrix } from "wgblas/classes/GpuMatrix";
      import { randomFloat32Array } from "wgblas/random";

      // Reshapes a flat row-major array into rows for console.table's 2D grid view.
      function toMatrix(A, rows, cols, lda = cols) {
        const out = [];
        for (let r = 0; r < rows; r++)
          out.push(Array.from(A.subarray(r * lda, r * lda + cols), (v) => +v.toFixed(4)));
        return out;
      }

      const device = await init();

      const n = 4;
      const x = randomFloat32Array(n, -10, 10);
      const A = randomFloat32Array(n * n, -10, 10);

      const xGpu = GpuVector.from(x);
      const AGpu = GpuMatrix.from(A, n, n, n, "row-major");

      console.log("x:", x);
      console.log("A (before):");
      console.table(toMatrix(A, n, n));

      // results stay on the GPU between steps
      await ssyr(device, "lower", n, 1.0, xGpu, 1, AGpu, AGpu.lda); // A += x*x^T
      await ssyr(device, "lower", n, 1.0, xGpu, 1, AGpu, AGpu.lda); // A += x*x^T again

      // single readback (GpuMatrix.read() is already dense — no lda padding to strip)
      const result = await AGpu.read();
      console.log("A (lower triangle, after two rank-1 updates):");
      console.table(toMatrix(result, n, n));

      xGpu.destroy();
      AGpu.destroy();

      if (typeof process !== "undefined") cleanup();

      Parameters

      • device: GPUDevice

        GPUDevice from init()

      • uplo: "lower" | "upper"

        'lower' to use the lower triangle, 'upper' to use the upper triangle

      • n: number

        order of the matrix A

      • alpha: number

        scalar multiplier for x*x^T

      • x: GpuVector

        GpuVector input vector (not mutated)

      • incx: number

        stride for x (must be a positive integer)

      • A: GpuMatrix

        GpuMatrix, mutated in place

      • lda: number

        leading dimension of A (must equal A.lda)

      Returns Promise<{ gpuTimeMs?: number }>

      Source code: ssyr.mjs (L15)

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