Hi, the first \vdots in the third row is not centered. \starttext \definemathmatrix[mymatrix][matrix:parentheses] \startformula \startmymatrix \NC A_1 \VL B_1 \NR \HL \NC \vdots \VL \vdots \NR \NC \vdots \NC \vdots \NR % there is probably something from here \HL \NC A_n \VL B_n \NR \stopmymatrix \stopformula \stoptext https://wiki.contextgarden.net/Matrix_in_maths#Other_formatting_example