问题描述:

I am writing a code and I am stuck in this problem. I have a summation that goes from 1 to a certain number, but one of the elements in the function including access to row/column zero (which is not allowed in Matlab).

So, for example:

`Let say v= 1 : 10`

And the function is:

`S(v) + M(v) S(v-1)`

I need to tell Matlab that if you get `S(0)`

return a value of `Zero`

.

`So for v=1 we get S(1)`

For v=2 we get S(2)+M(2) S(1)

For v=3 we get S(3)+M(3) S(2)

And so on.

Is there a way to do that?

Thank you.

Here's what I would have done: (res stores the result of the equation)

```
res(1)=S(1);
for v=2:10
res(v)=S(v)+M(v).*S(v-1);
end;
```

What if I have a complex function with ascending and descending index.

The function that I am trying to code is:

```
S(1) + (S(2)+M(1)*S(1))X + (S(3)+M(1)*S(2)+M(2)*S(1))X^2 + ...
```

So, you can have it as:

```
(S(v)+M(1)*S(v-1)+...+M(v-1)*S(1)) X^v-1
```

If you are using functions, you can return anything you want when zero is passed in.

For matrices, indexing is always one-based. Usually `t=0`

is represented by `A(1)`

. So just add one.