docs: add missing API docs

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Author: kgryte

lib/node_modules/@stdlib/blas/ext/base/dnansumpw/src/main.c

@@ -32,16 +32,33 @@
 *
 * -   Higham, Nicholas J. 1993. "The Accuracy of Floating Point Summation." _SIAM Journal on Scientific Computing_ 14 (4): 783–99. doi:[10.1137/0914050](https://doi.org/10.1137/0914050).
 *
-* @param N       number of indexed elements
-* @param X       input array
+* @param N        number of indexed elements
+* @param X        input array
 * @param strideX  stride length
-* @return        output value
+* @return         output value
 */
 double API_SUFFIX(stdlib_strided_dnansumpw)( const CBLAS_INT N, const double *X, const CBLAS_INT strideX ) {
 	CBLAS_INT ox = stdlib_strided_stride2offset( N, strideX );
 	return API_SUFFIX(stdlib_strided_dnansumpw_ndarray)( N, X, strideX, ox );
 }
 
+/**
+* Computes the sum of double-precision floating-point strided array elements, ignoring `NaN` values and using pairwise summation and alternative indexing semantics.
+*
+* ## Method
+*
+* -   This implementation uses pairwise summation, which accrues rounding error `O(log2 N)` instead of `O(N)`. The recursion depth is also `O(log2 N)`.
+*
+* ## References
+*
+* -   Higham, Nicholas J. 1993. "The Accuracy of Floating Point Summation." _SIAM Journal on Scientific Computing_ 14 (4): 783–99. doi:[10.1137/0914050](https://doi.org/10.1137/0914050).
+*
+* @param N        number of indexed elements
+* @param X        input array
+* @param strideX  stride length
+* @param offsetX  starting index
+* @return         output value
+*/
 double API_SUFFIX(stdlib_strided_dnansumpw_ndarray)( const CBLAS_INT N, const double *X, const CBLAS_INT strideX, const CBLAS_INT offsetX ) {
 	CBLAS_INT ix;
 	CBLAS_INT M;