Multiple selective values two matrix

Like this Yusra:-

Cheers

Terry

Functions are helpful if you might want to do this more than once and/or with different value of m.

Stuart

You already got your solution. I just wanted to explain why your approach did not work. Reason is that you used the vectors which are created as a subscript - hence the error message as a subscript must be an integer.

Your approach works OK if you just multliply the results of the subscript functions.

Here the vector dot product is used by Prime:

If you had an element-wise multiplication in mind so the result is again a vector, you would have to use vectorization:

But I am a little irritated as you use a value in vector dz as the number of elements to multiply. What if you would have chosen m:=dz₂ instead of m:=dz₃ ?? Obviously its not possible to multiply the first seven elements as dz contains only six elements. You may replace  m  by  min(m, last(z), last(dz)   to cope with this.

And I sure agree with Stuart that using a function to do the job could be quite beneficial.

You may use a more generic one which multiplies a contiguous range given the start and end index:

Or you could do without submatrix and vectorization by using a simple for-loop

Both functions don't use any error checking as of invalid indices...