L2 norm helpers

src/numz.zig

@@ -253,16 +253,39 @@ pub fn Matrix(rows: comptime_int, cols: comptime_int, T: type) type {
                 inline for (0..result.cols) |j| {
                     var sum: T = 0;
                     inline for (0..self.cols) |k| {
-                        if (@typeInfo(T) == .float)
-                            sum = @mulAdd(T, self.mat[i][k], other.mat[k][j], sum)
-                        else
-                            sum += self.mat[i][k] * other.mat[k][j];
+                        switch (@typeInfo(T)) {
+                            .float => sum = @mulAdd(T, self.mat[i][k], other.mat[k][j], sum),
+                            else => sum += self.mat[i][k] * other.mat[k][j],
+                        }
                     }
                     result.mat[i][j] = sum;
                 }
             }
             return result;
         }
+
+        pub fn normSquared(self: Self) T {
+            var n: T = 0;
+            inline for (self.mat) |row| {
+                inline for (row) |e| {
+                    switch (@typeInfo(T)) {
+                        .float => n = @mulAdd(T, e, e, n),
+                        else => n += e * e,
+                    }
+                }
+            }
+            return n;
+        }
+
+        pub const norm =
+            switch (@typeInfo(T)) {
+                .float => struct {
+                    fn norm(self: Self) T {
+                        return @sqrt(self.normSquared());
+                    }
+                }.norm,
+                else => @compileError("Connot take a square root on an integer matrix"),
+            };
     };
 }
 
@@ -467,3 +490,11 @@ test "stack scalar cols" {
     const expected: [1][6]f32 = .{.{ 1, 2, 3, 4, 5, 6 }};
     try std.testing.expectEqual(expected, m2.mat);
 }
+
+test "norm" {
+    const int = stackRows(u32, .{ 3, 4 });
+    try std.testing.expectEqual(25, int.normSquared());
+
+    const float = stackRows(f64, .{ 3, 4 });
+    try std.testing.expectEqual(5, float.norm());
+}