HP 15c Scientific manual Stack Operation for Matrix Calculations

174Section 12: Calculating with Matrices

∙Pressing ´mVdimensions the matrix specified in RI according to the dimensions in the X- and Y-registers.

∙Pressing lmVrecalls to the X- and Y-registers the dimensions of the matrix specified in RI.

∙Pressing GVor tVhas the same result as pressing

Gor tfollowed by the letter of the matrix specified in RI. (This is not actually a matrix operation – only the letter in the matrix descriptor is used.)

Conditional Tests on Matrix Descriptors

Four conditional tests – ~, T 0 (x≠ 0), T 5 (x = y), and T

6(x≠y) – can be performed with matrix descriptors in the X- and Y- registers, Conditional tests can be used to control program execution, as described in section 8.

If a matrix descriptor is in the X-register, the result of ~ will be false and the result of T 0 will be true (regardless of the element values in the matrix.)

If matrix descriptors are in the X- and Y-registers when T 5 or T6 conditional test is performed, x and y are equal if the same descriptor is in the X- and Y-registers, and not equal otherwise. The comparison is made between the descriptors themselves, not between the elements of the specified matrices.

Other conditional tests can't be used with matrix descriptors.

Stack Operation for Matrix Calculations

During matrix calculations, the contents of the stack registers shift much like they do during numeric calculations.

For some matrix calculations, the result is stored in the result matrix. The arguments – one or two descriptors or numbers in the X-register or the X- and Y-registers – are combined by the operation, and the descriptor of the result matrix is placed in the X-register. (The argument from the X-register is placed in the LAST X register.)