@tomleslie 

forgave me

i fixed my mistake

a1 := Matrix(3, 4, [1, 2, 3, 4, 7, 8, 9, 10, 13, 14, 15, 16]);

a2 := Matrix(3, 2, [5, 6, 11, 12, 17, 18]);
a3 := Matrix(2, [19, 20, 25, 26]);
a2 := Matrix(3, 2, [5, 6, 11, 12, 17, 18]);

@tomleslie 

hi

first thank you for your kindness

your output is

but i want

best regard

@Carl Love 

hi

your answer look like this

but my aim is writed matrix like this

be success