chore: Slight variable change

Author: sp301415

math/poly/asm_fft_test.go

@@ -13,7 +13,7 @@ func fftInPlaceRef(coeffs, tw []complex128) {
 	N := len(coeffs)
 
 	t := N
-	for m := 1; m < N; m <<= 1 {
+	for m := 1; m <= N/2; m <<= 1 {
 		t >>= 1
 		for i := 0; i < m; i++ {
 			j1 := i * t << 1
@@ -30,16 +30,14 @@ func invFFTInPlaceRef(coeffs, twInv []complex128) {
 	N := len(coeffs)
 
 	t := 1
-	for m := N; m > 1; m >>= 1 {
-		j1 := 0
-		h := m >> 1
-		for i := 0; i < h; i++ {
+	for m := N / 2; m >= 1; m >>= 1 {
+		for i := 0; i < m; i++ {
+			j1 := i * t << 1
 			j2 := j1 + t
 			for j := j1; j < j2; j++ {
 				U, V := coeffs[j], coeffs[j+t]
 				coeffs[j], coeffs[j+t] = U+V, (U-V)*twInv[i]
 			}
-			j1 += t << 1
 		}
 		t <<= 1
 	}
@@ -58,20 +56,20 @@ func TestFFTAssembly(t *testing.T) {
 
 	twRef := make([]complex128, N/2)
 	twInvRef := make([]complex128, N/2)
-	for j := 0; j < N/2; j++ {
-		e := -2 * math.Pi * float64(j) / float64(N)
-		twRef[j] = cmplx.Exp(complex(0, e))
-		twInvRef[j] = cmplx.Exp(-complex(0, e))
+	for i := 0; i < N/2; i++ {
+		e := -2 * math.Pi * float64(i) / float64(N)
+		twRef[i] = cmplx.Exp(complex(0, e))
+		twInvRef[i] = cmplx.Exp(-complex(0, e))
 	}
 	vec.BitReverseInPlace(twRef)
 	vec.BitReverseInPlace(twInvRef)
 
 	twist := make([]complex128, N)
 	twistInv := make([]complex128, N)
-	for j := 0; j < N; j++ {
-		e := 2 * math.Pi * float64(j) / float64(4*N)
-		twist[j] = cmplx.Exp(complex(0, e))
-		twistInv[j] = cmplx.Exp(-complex(0, e)) / complex(float64(N), 0)
+	for i := 0; i < N; i++ {
+		e := 2 * math.Pi * float64(i) / float64(4*N)
+		twist[i] = cmplx.Exp(complex(0, e))
+		twistInv[i] = cmplx.Exp(-complex(0, e)) / complex(float64(N), 0)
 	}
 
 	tw, twInv := genTwiddleFactors(N)

math/poly/poly_evaluator.go

@@ -96,9 +96,9 @@ func NewEvaluator[T num.Integer](N int) *Evaluator[T] {
 	tw, twInv := genTwiddleFactors(N / 2)
 
 	twMono := make([]complex128, 2*N)
-	for j := 0; j < 2*N; j++ {
-		e := -math.Pi * float64(j) / float64(N)
-		twMono[j] = cmplx.Exp(complex(0, e))
+	for i := 0; i < 2*N; i++ {
+		e := -math.Pi * float64(i) / float64(N)
+		twMono[i] = cmplx.Exp(complex(0, e))
 	}
 
 	twMonoIdx := make([]int, N/2)
@@ -125,27 +125,27 @@ func NewEvaluator[T num.Integer](N int) *Evaluator[T] {
 func genTwiddleFactors(N int) (tw, twInv []complex128) {
 	twFFT := make([]complex128, N/2)
 	twInvFFT := make([]complex128, N/2)
-	for j := 0; j < N/2; j++ {
-		e := -2 * math.Pi * float64(j) / float64(N)
-		twFFT[j] = cmplx.Exp(complex(0, e))
-		twInvFFT[j] = cmplx.Exp(-complex(0, e))
+	for i := 0; i < N/2; i++ {
+		e := -2 * math.Pi * float64(i) / float64(N)
+		twFFT[i] = cmplx.Exp(complex(0, e))
+		twInvFFT[i] = cmplx.Exp(-complex(0, e))
 	}
 	vec.BitReverseInPlace(twFFT)
 	vec.BitReverseInPlace(twInvFFT)
 
 	tw = make([]complex128, 0, N-1)
 	twInv = make([]complex128, 0, N-1)
 
-	for m, t := 1, N/2; m < N; m, t = m<<1, t>>1 {
+	for m, t := 1, N/2; m <= N/2; m, t = m<<1, t>>1 {
 		twFold := cmplx.Exp(complex(0, 2*math.Pi*float64(t)/float64(4*N)))
 		for i := 0; i < m; i++ {
 			tw = append(tw, twFFT[i]*twFold)
 		}
 	}
 
-	for m, t := N, 1; m > 1; m, t = m>>1, t<<1 {
+	for m, t := N/2, 1; m >= 1; m, t = m>>1, t<<1 {
 		twInvFold := cmplx.Exp(complex(0, -2*math.Pi*float64(t)/float64(4*N)))
-		for i := 0; i < m/2; i++ {
+		for i := 0; i < m; i++ {
 			twInv = append(twInv, twInvFFT[i]*twInvFold)
 		}
 	}