HP 15c - Manual (Page 208)

208 Appendix A: Error Conditions
+ or -, where the dimensions are incompatible.
*, where:
 the dimensions are incompatible; or
 the result is one of the arguments.
∕, where the matrix is not square.
scalar/matrix ÷, where the matrix is not square.
÷, where:
 the matrix in the X-register is not square;
 the dimensions are incompatible; or
 the result is the matrix in the X-register.
> 2, where the input is a scalar; or the number of rows is odd.
> 3, where the input is a scalar; or the number of columns is odd.
>
4, where the input is scalar.
> 5, where:
 the input is a scalar;
  the dimensions are incompatible; or
  the result is one of the arguments.
> 6, where:
 the input is scalar;
 the dimensions are incompatible (including the result); or
 the result is one of the arguments.
> 9, where the matrix is not square.
l m V, where contents of R
I
are scalar.
m V, where contents of R
I
are scalar.
O <, where the input is scalar.
p, where the number of columns is odd.
c, where the number of rows is odd.
Pr Error (Power Error)
Continuous Memory interrupted and reset because of power failure.