Need help with MATLAB error

\[ \begin{array}{l} \text { load('mnist_train.mat'); } \\ \text { load('mnist_test.mat'); } \end{array} \] \[ \begin{array}{l} \text { class }=10 ; \% \text { Number of classes (digits 0-9) } \\ \text { B_train = eye(class), labels_train; } \\ \text { B_test }=\text { eye(class), labels_test; } \end{array} \] A_train = reshape(images_train, [], size(images_train, 3)); A_test = reshape(images_test, [], size(images_test, 3)); \[ \begin{array}{l} \text { x_train = linsolve(A_train, B_train }) \text {; } \\ \text { x_test }=\text { linsolve (A_test, B_test }) ; \mid \end{array} \] Error using linselve First and second arguments must be single or double