You could continue to use textscan, you don't specify line endings and separators in the format string:
fid = fopen('test.txt');
B_a=textscan(fid,'%f%f%f%f%f','HeaderLines', 1);
fclose(fid);
B_a = cell2mat(B_a);
You could also use readtable to read as a table, then convert to a matrix. If the header of the your file made more sense, readtable could have used that to name the variables.
B_a = table2array(readtable('test.txt'));
B_a = readmatrix('test.txt'); %all done. It figures out the number of headerlines on its own.
