Scratch

Check to see if there is a repeating sequence of numbers? If so, then it is NOT an IRRATIONAL NUMBER.

If you just have a number and no other information, then, as nXIII said a while ago, that number is rational, because it has a finite number of (nonzero) digits.  End of story.

But it is possible to know a value is irrational if what you have is something other than just a number; for example, suppose you have a representation for algebraic equations in one variable.  You could use a list of the coefficients of the powers of x, starting from x^0 (the constant term).  So, the list (1 4 3) would represent 3x^2+4x+1=0.  Well, given such an equation, you can determine whether its solutions are rational or irrational.

So, for example, let's think about the square root of 2.  If you just have the number 1.414... to however many digits the computer gives you, that number is rational, and is not exactly equal to the square root of 2!  But if we use the list (-2 0 1) to represent the square root of 2 (because it's a root of the equation x^2-2=0) then you can prove that that number is irrational -- but you don't know any of its digits!     Of course you can use the equation to get a rational approximation to the value, too.  (I'm handwaving away the problem of multiple solutions to the equation; let's say we have some way of choosing the "principal" solution.)

But only the algebraic numbers are representable as solutions to polynomial equations.  (This is the definition of "algebraic number" so I'm not saying anything deep here.) Most numbers are not algebraic, including such interesting numbers as pi and e.  You'd have to have some other way to represent those.

But the bad news here is that the number of possible representations of anything in a computer is finite, so hardly any numbers are representable no matter how you want to do the representation.  (Even a computer with infinite memory, it turns out, could hardly represent any of the possible real numbers.)

This may be more than anyone wanted to know, but since nXIII gave a concise and full answer to the question as originally posed, and people kept talking about it, I figure y'all wanted some alternate ways to think about the question of rational vs. irrational numbers.

Made a new block... Anyone want to give it a try?

last [] characters of [] reversed.

So if you did last 3 characters of ABCD reversed you would get DCB

4 characters would give you DCBA.

weird, that should work......

markyparky56 wrote:

Rather strange block, what would you use it for?

I dunno, but it's fun expirementing with blocks and start a collection 

I already split them up! 

I just downloaded BYOB and I think I understand the basics, I don't understand how to make reporter and predicates (which is the same as boolean, right?) . I think we should add that to this.

EDIT: I know how to make reporters now, but can you make a dropdown?

Last edited by SSBBM (2010-07-14 17:05:57)

i know how to make a negative block.
[img src=costume.bmp]

EPIC FAIL.
Just Kidding!
Use the [report [(0-number)] ] block.
Or, like i do, use the [report [(number)*-1] ]

Scratchthatguys wrote:

bbbeb wrote:

EPIC FAIL.
Just Kidding!
Use the [report [(0-number)] ] block.
Or, like i do, use the [report [(number)*-1] ]

were you talking to me?

Yeah he was. His point was that you could use the [report []] block instead of the [say []] to make it a more realistic block.

bbbeb wrote:

[report ([text] of [ScratchReallyRocks] ]
He's right.

I'm always right  well, not ALWAYS...

nXIII wrote:

soupoftomato wrote:

Block 3: inverse of ()
This block gives the inverse (opposite) of a number.

1. Click "Make a block," and select "Operators," as the block group. For the type of block, you need to select the round, "reporter" block. In the naming bar, type, "inverse of." Press OK.

2. You should see the hat block with a block that says, "inverse of," in it. Remember how we added variables where the plus signs were last time? Do that after "of." When it asks for it's name, type, "number."

3. Because there are two types of inverses, positive, and negative. We need the script to check if the number is positive or negative. Put on if statement that says, "if number(the variable we made)> 0." And another if statement that says, "if number < 0."

4. Make a new variable called number1. In the first if, put "set number1 to (0-number). In the second if, put, "set number to (-1*number).

5. Now you're done and your scripts should look like this:

http://img213.imageshack.us/img213/2454/inverseof.gif

6. Press OK

Exactly what are you doing here?!
subtracting from zero and multiplying by negative one always produces the same result! I mean, really? I quote you saying, "two types of inverses, positive and negative." No there aren't. What the heck are you talking about. Are you trying to say, "the inverse of a positive number is negative, and the inverse of a negative number is positive"? Because its sign doesn't matter! Let's try a few examples, shall we?

#1: inverse of 3
0 - 3 = -3 error, 0 is not positive or negative, impossible to do. 0 is a nertaul.
3 * -1 = -3 error, Impossible to do in this block.

#2: inverse of -10
0 - (-10) = 10 error, Inverse of 10 is -10, inverse of -10 is 10. As I Said, 0 is not positive or negative. Impossible.
-10 * -1 = 10 Correct.

#3: inverse of 0
0 - 0 = 0 True. But nothing to do with the inverse block. Error, the 0 again!
0 * -1 = 0 error, 0 is not positive or negative, so impossible.

One comment from rdococ: Too much errors I have caught.
I think that covers everything, doesn't it? See what I mean?

It covers up nothing. 4 or 5 out of 6 errors.

nXIII wrote:

rdococ wrote:

nXIII wrote:

soupoftomato wrote:

Block 3: inverse of ()
This block gives the inverse (opposite) of a number.

1. Click "Make a block," and select "Operators," as the block group. For the type of block, you need to select the round, "reporter" block. In the naming bar, type, "inverse of." Press OK.

2. You should see the hat block with a block that says, "inverse of," in it. Remember how we added variables where the plus signs were last time? Do that after "of." When it asks for it's name, type, "number."

3. Because there are two types of inverses, positive, and negative. We need the script to check if the number is positive or negative. Put on if statement that says, "if number(the variable we made)> 0." And another if statement that says, "if number < 0."

4. Make a new variable called number1. In the first if, put "set number1 to (0-number). In the second if, put, "set number to (-1*number).

5. Now you're done and your scripts should look like this:

http://img213.imageshack.us/img213/2454/inverseof.gif

6. Press OK

Exactly what are you doing here?!
subtracting from zero and multiplying by negative one always produces the same result! I mean, really? I quote you saying, "two types of inverses, positive and negative." No there aren't. What the heck are you talking about. Are you trying to say, "the inverse of a positive number is negative, and the inverse of a negative number is positive"? Because its sign doesn't matter! Let's try a few examples, shall we?

#1: inverse of 3
0 - 3 = -3 error, 0 is not positive or negative, impossible to do. 0 is a nertaul.
3 * -1 = -3 error, Impossible to do in this block.

#2: inverse of -10
0 - (-10) = 10 error, Inverse of 10 is -10, inverse of -10 is 10. As I Said, 0 is not positive or negative. Impossible.
-10 * -1 = 10 Correct.

One comment from rdococ: Too much errors I have caught.
I think that covers everything, doesn't it? See what I mean?

It covers up nothing. 4 or 5 out of 6 errors.

um... what are you on about?
You can subtract stuff from zero.
0 - 10 = -10. Try it on a calculator.

just use


( 0 - abs of (number) )