feat: adds branch 1 logic

Author: DivitJain26

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

@@ -14,4 +14,151 @@
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
-*/
+*/
+
+'use strict';
+
+// MODULES //
+
+var reinterpret = require( '@stdlib/strided/base/reinterpret-complex64' );
+var isRowMajor = require( '@stdlib/ndarray/base/assert/is-row-major' );
+var f32 = require( '@stdlib/number/float64/base/to-float32' );
+
+
+// MAIN //
+
+/**
+* Solves one of the systems of equations `A*x = b` or `A^T*x = b` or `A^H*x = b` where `b` and `x` are `N` element complex vectors and `A` is an `N` by `N` unit, or non-unit, upper or lower triangular complex matrix.
+*
+* @private
+* @param {string} uplo - specifies whether `A` is an upper or lower triangular matrix
+* @param {string} trans - specifies whether `A` should be transposed, conjugate-transposed, or not transposed
+* @param {string} diag - specifies whether `A` has a unit diagonal
+* @param {NonNegativeInteger} N - number of elements along each dimension of `A`
+* @param {Complex64Array} A - input matrix
+* @param {integer} strideA1 - stride of the first dimension of `A`
+* @param {integer} strideA2 - stride of the second dimension of `A`
+* @param {NonNegativeInteger} offsetA - starting index for `A`
+* @param {Complex64Array} x - input vector
+* @param {integer} strideX - `x` stride length
+* @param {NonNegativeInteger} offsetX - starting index for `x`
+* @returns {Complex64Array} `x`
+*
+* @example
+* var Complex64Array = require( '@stdlib/array/complex64' );
+*
+* var A = new Complex64Array( [  ] );
+* var x = new Complex64Array( [  ] );
+*
+* ctrsv( 'lower', 'no-transpose', 'non-unit', 3, A, 2, 1, 0, x, 1, 0 );
+* // x => <Complex64Array>[ 0.0, 2.0, 0.0, 16.0, 0.0, 46.0 ]
+*/
+function ctrsv( uplo, trans, diag, N, A, strideA1, strideA2, offsetA, x, strideX, offsetX ) { // eslint-disable-line max-params, max-len
+	var nonunit;
+	var viewA;
+	var viewX;
+	var retmp;
+	var imtmp;
+	var magsq;
+	var remul;
+	var immul;
+	var isrm;
+	var sign;
+	var rex;
+	var imx;
+	var rea;
+	var ima;
+	var ix0;
+	var ix1;
+	var sa0;
+	var sa1;
+	var oa2;
+	var ox;
+	var sx;
+	var oa;
+	var i0;
+	var i1;
+	var ia;
+
+	// Layout
+	isrm = isRowMajor( [ strideA1, strideA2 ] );
+
+	// Diagonal
+	nonunit = ( diag === 'non-unit' );
+
+	// Reinterpret arrays to raw numeric views
+	viewA = reinterpret( A, 0 );
+	viewX = reinterpret( x, 0 );
+
+	// Set sign to handle conjugation: flip the imaginary part for conjugate-transpose
+	if ( trans === 'conjugate-transpose' ) {
+		sign = -1;
+	} else {
+		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;
+
+	// Vector strides
+	sx = strideX * 2;
+
+	if (
+		( !isrm && uplo === 'upper' && trans === 'no-transpose' ) ||
+		( isrm && uplo === 'lower' && trans !== 'no-transpose' )
+	) {
+		ix1 = ox + ( ( N - 1 ) * sx );
+		for ( i1 = N - 1; i1 >= 0; i1-- ) {
+			rex = viewX[ ix1 ];
+			imx = viewX[ ix1 + 1 ];
+			if ( rex !== 0.0 || imx !== 0.0 ) {
+				oa2 = oa + ( sa1 * i1 );
+				if ( nonunit ) {
+					ia = oa2 + ( sa0 * i1 );
+					rea = viewA[ ia ];
+					ima = sign * viewA[ ia + 1 ];
+					magsq = f32( ( rea * rea ) + ( ima * ima ) );
+					retmp = f32( f32( ( rex * rea ) + ( imx * ima ) ) / magsq );
+					imtmp = f32( f32( ( imx * rea ) - ( rex * ima ) ) / magsq );
+					viewX[ ix1 ] = retmp;
+					viewX[ ix1 + 1 ] = imtmp;
+				} else {
+					retmp = rex;
+					imtmp = imx;
+				}
+				ix0 = ix1;
+				for ( i0 = i1 - 1; i0 >= 0; i0-- ) {
+					ix0 -= sx;
+					ia = oa2 + ( sa0 * i0 );
+					rea = viewA[ ia ];
+					ima = sign * viewA[ ia + 1 ];
+					rex = viewX[ ix0 ];
+					imx = viewX[ ix0 + 1 ];
+					remul = f32( ( retmp * rea ) - ( imtmp * ima ) );
+					immul = f32( ( retmp * ima ) + ( imtmp * rea ) );
+					viewX[ ix0 ] = f32( rex - remul );
+					viewX[ ix0 + 1 ] = f32( imx - immul );
+				}
+			}
+			ix1 -= sx;
+		}
+		return x;
+	}
+	
+}
+
+
+// EXPORTS //
+
+module.exports = ctrsv;