refactor: update index increment to stride addition

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Author: DivitJain26

lib/node_modules/@stdlib/blas/base/cgemv/lib/base.js

@@ -106,9 +106,8 @@ function cgemv( trans, M, N, alpha, A, strideA1, strideA2, offsetA, x, strideX,
 	var xlen;
 	var ylen;
 	var sign;
-	var sa0;
-	var sa1;
-	var oa2;
+	var da0;
+	var da1;
 	var rea;
 	var ima;
 	var rex;
@@ -166,16 +165,6 @@ function cgemv( trans, M, N, alpha, A, strideA1, strideA2, offsetA, x, strideX,
 		sign = 1;
 	}
 
-	if ( isrm ) {
-		// For row-major matrices, the last dimension has the fastest changing index...
-		sa0 = strideA2 * 2;                     // offset increment for innermost loop
-		sa1 = strideA1 * 2;                     // offset increment for outermost loop
-	} else { // isColMajor
-		// For column-major matrices, the first dimension has the fastest changing index...
-		sa0 = strideA1 * 2;                     // offset increment for innermost loop
-		sa1 = strideA2 * 2;                     // offset increment for outermost loop
-	}
-
 	// Vector indexing base
 	oa = offsetA * 2;
 	ox = offsetX * 2;
@@ -190,42 +179,66 @@ function cgemv( trans, M, N, alpha, A, strideA1, strideA2, offsetA, x, strideX,
 		( !isrm && !isTransposed( trans ) ) ||
 		( isrm && isTransposed( trans ) )
 	) {
+		if ( isrm ) {
+			da0 = strideA2 * 2;
+			da1 = ( strideA1 * 2 ) - ( ylen * strideA2 * 2 );
+		} else {
+			da0 = strideA1 * 2;
+			da1 = ( strideA2 * 2 ) - ( ylen * strideA1 * 2 );
+		}
+		ia = oa;
+		ix = ox;
 		for ( i1 = 0; i1 < xlen; i1++ ) {
-			ix = ox + ( i1 * sx );
-			oa2 = oa + ( i1 * sa1 );
 			rex = viewX[ ix ];
 			imx = viewX[ ix + 1 ];
 			retmp = f32( ( realpha * rex ) - ( imalpha * imx ) );
 			imtmp = f32( ( realpha * imx ) + ( imalpha * rex ) );
-			for ( i0 = 0; i0 < ylen; i0++ ) {
-				ia = oa2 + ( i0 * sa0 );
-				rea = viewA[ ia ];
-				ima = sign * viewA[ ia + 1 ];
-				iy = oy + ( i0 * sy );
-				muladd( rea, ima, retmp, imtmp, viewY[ iy ], viewY[ iy + 1 ], viewY, 1, iy ); // eslint-disable-line max-len
+			if ( retmp === 0.0 && imtmp === 0.0 ) {
+				ia += da0 * ylen;
+			} else {
+				iy = oy;
+				for ( i0 = 0; i0 < ylen; i0++ ) {
+					rea = viewA[ ia ];
+					ima = sign * viewA[ ia + 1 ];
+					muladd( rea, ima, retmp, imtmp, viewY[ iy ], viewY[ iy + 1 ], viewY, 1, iy ); // eslint-disable-line max-len
+					iy += sy;
+					ia += da0;
+				}
 			}
+			ix += sx;
+			ia += da1;
 		}
 		return y;
 	}
 
 	// Form: y = α*A^T*x + y
 	// ( !isrm && isTransposed( trans ) ) || ( isrm && !isTransposed( trans ) )
+	if ( isrm ) {
+		da0 = strideA2 * 2;
+		da1 = ( strideA1 * 2 ) - ( xlen * strideA2 * 2 );
+	} else {
+		da0 = strideA1 * 2;
+		da1 = ( strideA2 * 2 ) - ( xlen * strideA1 * 2 );
+	}
+	ia = oa;
+	iy = oy;
 	for ( i1 = 0; i1 < ylen; i1++ ) {
-		oa2 = oa + ( i1 * sa1 );
 		retmp = 0.0;
 		imtmp = 0.0;
+		ix = ox;
 		for ( i0 = 0; i0 < xlen; i0++ ) {
-			ia = oa2 + ( i0 * sa0 );
-			ix = ox + ( i0 * sx );
 			rea = viewA[ ia ];
 			ima = sign * viewA[ ia + 1 ];
 			rex = viewX[ ix ];
 			imx = viewX[ ix + 1 ];
 			retmp = f32( retmp + f32( ( rea * rex ) - ( ima * imx ) ) );
 			imtmp = f32( imtmp + f32( ( rea * imx ) + ( ima * rex ) ) );
+			ix += sx;
+			ia += da0;
 		}
-		iy = oy + ( i1 * sy );
 		muladd( realpha, imalpha, retmp, imtmp, viewY[ iy ], viewY[ iy + 1 ], viewY, 1, iy ); // eslint-disable-line max-len
+		iy += sy;
+		ia += da1;
 	}
 	return y;
 }