This example visualizes the correlations among 26 random variables (columns 'a' through 'z') in a triangular heatmap matrix. Synthetic data is generated with random numbers, and a correlation matrix is computed using `jz.arr.correlationMatrix` from the jeezy library, then laid out with the data2grid library. D3 v4 renders the grid as SVG rectangles, with colors mapped through a chroma-js scale from tomato to steelblue. Hovering highlights the corresponding axis ticks and displays a tooltip with the exact correlation value, while the color legend uses an SVG linearGradient.