function fromArray( buf, arr ) {
	var len;
	var v;
	var i;
	var j;

	len = arr.length;
	j = 0;
	for ( i = 0; i < len; i++ ) {
		v = arr[ i ];
		if ( !isComplexLike( v ) ) {
			return null;
		}
		buf[ j ] = realf( v );
		buf[ j+1 ] = imagf( v );
		j += 2; // stride
	}
	return buf;
}
Returns a strided array of real and imaginary components.

@private
@param {Float32Array} buf - output array
@param {Array} arr - array containing complex numbers
@returns {(Float32Array|null)} output array or null