Conditionally use fma

utils/constmatrix/Cargo.toml

@@ -6,5 +6,6 @@ edition = "2018"
 
 [dependencies]
 approx = { version = "0.4.0", optional = true }
+cfg-if = "1.0.0"
 float = { path = "../float" }
 num-traits = "0.2.14"

utils/constmatrix/src/lib.rs

@@ -131,7 +131,13 @@ impl<const M: usize, const P: usize> Matrix<Float, M, P> {
                     lhs[(i, 0)] * rhs[(0, j)]
                 };
                 for k in 1..N {
-                    t = Float::mul_add(lhs[(i, k)], rhs[(k, j)], t);
+                    cfg_if::cfg_if!(
+                        if #[cfg(target_feature="fma")] {
+                            t = Float::mul_add(lhs[(i, k)], rhs[(k, j)], t);
+                        } else {
+                            t = t + lhs[(i, k)]*rhs[(k, j)];
+                        }
+                    );
                 }
                 self[(i, j)] = t;
             }