mat: document that Trace will use a Tracer's implementation
MODIFY
mat/matrix.go
mat/matrix.go
@@ -938,7 +938,8 @@ type Tracer interface {
}
// Trace returns the trace of the matrix. Trace will panic if the
-// matrix is not square.
+// matrix is not square. If a is a Tracer, its Trace method will be
+// used to calculate the matrix trace.
func Trace(a Matrix) float64 {
m, _ := untransposeExtract(a)
if t, ok := m.(Tracer); ok {

mat: document that Trace will use a Tracer's implementation