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    Function dswap

    • Swaps the elements of two double-precision vectors: $$x \leftrightarrow y$$ — double-double (Dekker) f64 emulation of sswap, since WGSL has no native f64 type.

      import { init, cleanup } from "wgblas";
      import { dswap } from "wgblas/dswap";

      const device = await init();

      const n = 5;
      const x = new Float64Array([1, 2, 3, 4, 5]);
      const y = new Float64Array([10, 20, 30, 40, 50]);

      console.log("x before:", x);
      console.log("y before:", y);
      const { x: resultX, y: resultY } = await dswap(device, n, x, 1, y, 1);
      console.log("x after: ", resultX);
      console.log("y after: ", resultY);
      if (typeof process !== "undefined") cleanup();

      Browser (standalone HTML):

      <!doctype html>
      <html lang="en">
        <head>
          <meta charset="UTF-8" />
          <title>dswap — 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, dswap, cleanup } = window.wgblas;

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

              const n = 5;
              const x = new Float64Array([1, 2, 3, 4, 5]);
              const y = new Float64Array([10, 20, 30, 40, 50]);

              const xBefore = Array.from(x).map(v => v.toFixed(4)).join(", ");
              const yBefore = Array.from(y).map(v => v.toFixed(4)).join(", ");

              const { x: resultX, y: resultY } = await dswap(device, n, x, 1, y, 1);

              document.getElementById("out").textContent =
                "x before: " + xBefore +
                "\ny before: " + yBefore +
                "\nx after:  " + Array.from(resultX).map(v => v.toFixed(4)).join(", ") +
                "\ny after:  " + Array.from(resultY).map(v => v.toFixed(4)).join(", ");

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

      Parameters

      • device: GPUDevice

        GPUDevice from init()

      • n: number

        number of elements to swap (must be a positive integer)

      • x: Float64Array

        Float64Array first input/output vector

      • incx: number

        stride for x (must be a positive integer)

      • y: Float64Array

        Float64Array second input/output vector

      • incy: number

        stride for y (must be a positive integer)

      Returns Promise<
          | { x: Float64Array; y: Float64Array }
          | { gpuTimeMs: number; x: Float64Array; y: Float64Array },
      >

      Source code: dswap.mjs (L22)

    • Swaps the elements of two double-precision vectors: $$x \leftrightarrow y$$ — GPU-resident overload; see the Float64Array overload above for the routine itself.

      import { init, cleanup } from "wgblas";
      import { dswap } from "wgblas/dswap";
      import { dscal } from "wgblas/dscal";
      import { GpuVector } from "wgblas/classes/GpuVector";

      const device = await init();

      const n = 5;
      const alpha = 2.0;
      const x = new Float64Array([1, 2, 3, 4, 5]);
      const y = new Float64Array([10, 20, 30, 40, 50]);

      const xGpu = GpuVector.from(x);
      const yGpu = GpuVector.from(y);

      console.log("x:               ", x);
      console.log("y:               ", y);

      await dswap(device, n, xGpu, 1, yGpu, 1);
      await dscal(device, n, alpha, xGpu, 1);

      // single readback
      const resultX = await xGpu.read();
      const resultY = await yGpu.read();
      console.log("x (2 * orig y):  ", resultX);
      console.log("y (orig x):      ", resultY);

      xGpu.destroy();
      yGpu.destroy();
      if (typeof process !== "undefined") cleanup();

      Parameters

      • device: GPUDevice

        GPUDevice from init()

      • n: number

        number of elements to swap (must be a positive integer)

      • x: GpuVector

        GpuVector first input/output vector (must be Float64Array-backed, mutated in place)

      • incx: number

        stride for x (must be a positive integer)

      • y: GpuVector

        GpuVector second input/output vector (must be Float64Array-backed, mutated in place)

      • incy: number

        stride for y (must be a positive integer)

      Returns Promise<{} | { gpuTimeMs: number }>

      Source code: dswap.mjs (L22)

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