Reciprocal

Biologists call that reciprocal altruism. OK.

So let's just multiply by the reciprocal.

Let me just take the reciprocal of this.

Learning between grown ups and kids should be reciprocal.

And they're sort of two reciprocal and dynamically interacting systems.

I'm going to ask is aà   c reciprocal?

To code it's reciprocal link, I'm going to use recursion.

And, of course, the human population has its own reciprocal obligations.

This is equivalent to 9 4 times the reciprocal of this.

If we don't have a reciprocal link in the graph, we're going to include node in the calculation if the link nodeà   page is not reciprocal.

So if we have 4 5 here, that'll be 5 4, the reciprocal.

And then we just multiply both sides times the reciprocal of seven nine.

Notice we went from a division to a multiplication, and we took the reciprocal.

But dividing by a fraction is the same thing as multiplying by the reciprocal.

The reciprocal of that is now the probability that we picked any particular pair.

You can also do 1. over V to do the element wise reciprocal of

What we want to know is is aà   c a reciprocal link?

So a à   c is not reciprocal and we should include a.

If we want to get to one eighth, which is a reciprocal of 8.

Remember, you see a negative exponent, that just means the reciprocal of the positive exponent.

The answer is no. We can't, which means that aà   c is not reciprocal.

We're changing the division operation to a multiplication, and we're taking the reciprocal of the 7 4.

Then we want to know whether we have that reciprocal link or not. We include the page.

We just have to multiply both sides times the reciprocal of the coefficient on the left hand side.

So, we take the reciprocal of that multiplied by Nv that gives us the fraction that we're looking for.

And finally, the inverse of a matrix is analogous to taking the reciprocal or inverting a regular scaler number.

So aà   c is not reciprocal in this case, and we should include a in c's calculation.

Dividing by 1 5 is the same thing as multiplying by the reciprocal of 1 5, which is 5 1.

Now, just as a review here, we've already seen that dividing by a number is equal to multiplying by its reciprocal.

And we saw in several videos already that dividing by a fraction is the same thing as multiplying by its reciprocal.

So remember, whenever you see that negative, what my brain always does is say, I need to take the reciprocal here.

If there is a path in other words, if reciprocal link graphs in the same graph we've got the same source.

If we want the reciprocal of 2 right over here, we have to just raise 8 to the negative one third.

For this question you're asked to modify the compute ranks code in order to take into consideration whether links are reciprocal or not.

If two friends have a reciprocal transaction, like selling a car, it's well known that this can be a source of tension or awkwardness.

For the reciprocal of 7 4, you swap the numerator and denominator, or the top number and the bottom number, and you get 4 7.

Now, whenever you're dividing any fractions, you just have to remember that dividing by a fraction is the same thing as multiplying by its reciprocal.

So a, another way to think about it is, you're going to take the reciprocal of this and raise it, and raise it to the positive exponent.

It's a reciprocal link if there is a path from c back to a of at most length k where k is a number that's given to us.

Yes, we can, because there is a direct link from b to a, which means that aà   c is reciprocal and we should not include a.

So 2 you could say, well, this is gonna be the same thing, 2 to the negative 4 is going to be the same thing as taking my reciprocal.

Now, when we divide by a fraction, we just have to remember that that is the same thing, that is completely equivalent to multiplying times the reciprocal of the fraction.

If k is 0 that was the first case we looked at in the example then we have a reciprocal link whenever the destination and the source are the same.

We're going to code a procedure to check whether aà   c is reciprocal, and then we're going to edit the code and compute ranks to take that into consideration.