build.zig

const std = @import("std");

pub fn build(b: *std.Build) void {
    const target = b.standardTargetOptions(.{});
    const optimize = b.standardOptimizeOption(.{});
    const target_os = target.result.os.tag;

    // OpenBLAS options
    const openblas_include = b.option([]const u8, "openblas-include", "Path to OpenBLAS include directory");
    const openblas_lib = b.option([]const u8, "openblas-lib", "Path to OpenBLAS library directory");

    // Main module
    const mod = b.addModule("lobpcg", .{
        .root_source_file = b.path("src/lobpcg.zig"),
        .target = target,
        .optimize = optimize,
    });

    // Link BLAS/LAPACK
    linkLinearAlgebra(mod, target_os, openblas_include, openblas_lib);

    // Tests
    const tests = b.addTest(.{
        .root_module = mod,
    });

    const run_tests = b.addRunArtifact(tests);
    const test_step = b.step("test", "Run unit tests");
    test_step.dependOn(&run_tests.step);
}

fn linkLinearAlgebra(
    mod: *std.Build.Module,
    target_os: std.Target.Os.Tag,
    openblas_include: ?[]const u8,
    openblas_lib: ?[]const u8,
) void {
    if (target_os == .macos) {
        mod.linkFramework("Accelerate", .{});
    } else {
        if (openblas_include) |inc| mod.addIncludePath(.{ .cwd_relative = inc });
        if (openblas_lib) |lib| mod.addLibraryPath(.{ .cwd_relative = lib });
        mod.linkSystemLibrary("openblas", .{});
        mod.linkSystemLibrary("lapack", .{});
    }
}