Cannot retrieve matrix from an xml file using FileStorage

I am storing features in form of a matrix in an xml file using FileStorage FileStorage f("trial.xml",FileStorage::WRITE); Mat feature; f<<"feature"<18

f

3.35365832e-001 1.21951215e-002 9.14634094e-002 6.30081296e-002 3.31300795e-001 1.01626012e-002 9.95934904e-002 5.69105670e-002 However, I cannot retrive the matrix from the xml file. FileStorage fs("trial.xml",FileStorage::READ); Mat data; fs["data"]>>data; cout<