blas/gonum: clean up and fix parameter checks

blas/gonum/dgemm.go

@@ -65,7 +65,7 @@ func (Implementation) Dgemm(tA, tB blas.Transpose, m, n, k int, alpha float64, a
 	}
 
 	// Quick return if possible.
-	if m == 0 || n == 0 || ((alpha == 0 || k == 0) && beta == 1) {
+	if m == 0 || n == 0 {
 		return
 	}
 
@@ -91,6 +91,11 @@ func (Implementation) Dgemm(tA, tB blas.Transpose, m, n, k int, alpha float64, a
 		panic(shortC)
 	}
 
+	// Quick return if possible.
+	if (alpha == 0 || k == 0) && beta == 1 {
+		return
+	}
+
 	// scale c
 	if beta != 1 {
 		if beta == 0 {

blas/gonum/level1double.go

@@ -23,7 +23,7 @@ func (Implementation) Dnrm2(n int, x []float64, incX int) float64 {
 		}
 		return 0
 	}
-	if incX > 0 && (n-1)*incX >= len(x) {
+	if len(x) <= (n-1)*incX {
 		panic(shortX)
 	}
 	if n < 2 {
@@ -97,7 +97,7 @@ func (Implementation) Dasum(n int, x []float64, incX int) float64 {
 		}
 		return 0
 	}
-	if incX > 0 && (n-1)*incX >= len(x) {
+	if len(x) <= (n-1)*incX {
 		panic(shortX)
 	}
 	if incX == 1 {
@@ -123,15 +123,15 @@ func (Implementation) Idamax(n int, x []float64, incX int) int {
 		}
 		return -1
 	}
-	if incX > 0 && (n-1)*incX >= len(x) {
+	if len(x) <= (n-1)*incX {
 		panic(shortX)
 	}
 	if n < 2 {
 		if n == 1 {
 			return 0
 		}
 		if n == 0 {
-			return -1 // Netlib returns invalid index when n == 0
+			return -1 // Netlib returns invalid index when n == 0.
 		}
 		panic(nLT0)
 	}
@@ -175,10 +175,10 @@ func (Implementation) Dswap(n int, x []float64, incX int, y []float64, incY int)
 		}
 		panic(nLT0)
 	}
-	if (incX > 0 && (n-1)*incX >= len(x)) || (incX < 0 && (1-n)*incX >= len(x)) {
+	if (incX > 0 && len(x) <= (n-1)*incX) || (incX < 0 && len(x) <= (1-n)*incX) {
 		panic(shortX)
 	}
-	if (incY > 0 && (n-1)*incY >= len(y)) || (incY < 0 && (1-n)*incY >= len(y)) {
+	if (incY > 0 && len(y) <= (n-1)*incY) || (incY < 0 && len(y) <= (1-n)*incY) {
 		panic(shortY)
 	}
 	if incX == 1 && incY == 1 {
@@ -217,10 +217,10 @@ func (Implementation) Dcopy(n int, x []float64, incX int, y []float64, incY int)
 		}
 		panic(nLT0)
 	}
-	if (incX > 0 && (n-1)*incX >= len(x)) || (incX < 0 && (1-n)*incX >= len(x)) {
+	if (incX > 0 && len(x) <= (n-1)*incX) || (incX < 0 && len(x) <= (1-n)*incX) {
 		panic(shortX)
 	}
-	if (incY > 0 && (n-1)*incY >= len(y)) || (incY < 0 && (1-n)*incY >= len(y)) {
+	if (incY > 0 && len(y) <= (n-1)*incY) || (incY < 0 && len(y) <= (1-n)*incY) {
 		panic(shortY)
 	}
 	if incX == 1 && incY == 1 {
@@ -256,10 +256,10 @@ func (Implementation) Daxpy(n int, alpha float64, x []float64, incX int, y []flo
 		}
 		panic(nLT0)
 	}
-	if (incX > 0 && (n-1)*incX >= len(x)) || (incX < 0 && (1-n)*incX >= len(x)) {
+	if (incX > 0 && len(x) <= (n-1)*incX) || (incX < 0 && len(x) <= (1-n)*incX) {
 		panic(shortX)
 	}
-	if (incY > 0 && (n-1)*incY >= len(y)) || (incY < 0 && (1-n)*incY >= len(y)) {
+	if (incY > 0 && len(y) <= (n-1)*incY) || (incY < 0 && len(y) <= (1-n)*incY) {
 		panic(shortY)
 	}
 	if alpha == 0 {
@@ -289,7 +289,7 @@ func (Implementation) Daxpy(n int, alpha float64, x []float64, incX int, y []flo
 //  c = a/r, the cosine of the plane rotation
 //  s = b/r, the sine of the plane rotation
 //
-// NOTE: There is a discrepancy between the refence implementation and the BLAS
+// NOTE: There is a discrepancy between the reference implementation and the BLAS
 // technical manual regarding the sign for r when a or b are zero.
 // Drotg agrees with the definition in the manual and other
 // common BLAS implementations.
@@ -444,10 +444,10 @@ func (Implementation) Drot(n int, x []float64, incX int, y []float64, incY int,
 		}
 		panic(nLT0)
 	}
-	if (incX > 0 && (n-1)*incX >= len(x)) || (incX < 0 && (1-n)*incX >= len(x)) {
+	if (incX > 0 && len(x) <= (n-1)*incX) || (incX < 0 && len(x) <= (1-n)*incX) {
 		panic(shortX)
 	}
-	if (incY > 0 && (n-1)*incY >= len(y)) || (incY < 0 && (1-n)*incY >= len(y)) {
+	if (incY > 0 && len(y) <= (n-1)*incY) || (incY < 0 && len(y) <= (1-n)*incY) {
 		panic(shortY)
 	}
 	if incX == 1 && incY == 1 {
@@ -488,10 +488,10 @@ func (Implementation) Drotm(n int, x []float64, incX int, y []float64, incY int,
 		}
 		panic(nLT0)
 	}
-	if (incX > 0 && (n-1)*incX >= len(x)) || (incX < 0 && (1-n)*incX >= len(x)) {
+	if (incX > 0 && len(x) <= (n-1)*incX) || (incX < 0 && len(x) <= (1-n)*incX) {
 		panic(shortX)
 	}
-	if (incY > 0 && (n-1)*incY >= len(y)) || (incY < 0 && (1-n)*incY >= len(y)) {
+	if (incY > 0 && len(y) <= (n-1)*incY) || (incY < 0 && len(y) <= (1-n)*incY) {
 		panic(shortY)
 	}
 
@@ -590,15 +590,15 @@ func (Implementation) Dscal(n int, alpha float64, x []float64, incX int) {
 		}
 		return
 	}
-	if (n-1)*incX >= len(x) {
-		panic(shortX)
-	}
 	if n < 1 {
 		if n == 0 {
 			return
 		}
 		panic(nLT0)
 	}
+	if (n-1)*incX >= len(x) {
+		panic(shortX)
+	}
 	if alpha == 0 {
 		if incX == 1 {
 			x = x[:n]