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Discussion posts for script bignumbers.r

1
guest2
27-Mar-2007 17:16

Edited:
guest2
27-Mar-2007 17:19

hello
i had a look on your script.
yes it works,  but it is very slow even if the code was optimized.

there is better ways, search on Internet for some good theories:

and have a look on what follows:

[code]
mul: func [n1 n2 /local tmp res len a b c d][

 ; n1 * n2 can be decomposed in four numbers, following the formula 
 (a + b) * (c + d).

 ; The goal is to decompose them into smaller numbers (recursivly) 
 until we can use the native mult operation
	; of rebol.

 ; Then, the big number is rebuild by addition and concatenation of 
 intermediate results. 
	len: max length? n1 length? n2
 if len < 5 [return to string! (to integer! n1) * to integer! n2]
	res: cp ""
	if 0 = len: min 4 min length? n1 length? n2 [return ""]
	a: cp/part n1 (length? n1) - len
	b: at n1 (length? n1) - len + 1
	c: cp/part n2 (length? n2) - len
	d: at n2 (length? n2) - len + 1
	res: mul b d
	tmp: add mul a d mul c b

 either len < length? res [tmp: add tmp cp/part res (length? res) 
 - len][insert/dup res "0" len - length? res]
	res: append tmp at res (length? res) - len + 1
	tmp: mul a c
	len: len * 2

 either len < length? res [tmp: add tmp cp/part res (length? res) 
 - len][insert/dup res "0" len - length? res]
	append tmp at res (length? res) - len  + 1
]

add: func [n1 n2 /local len tmp res a b c d][

 ; same as above, n1 and n2 are decomposed in smaller numbers, recursivly 
 until Rebol can operate them nativly.

 if 10 > max length? n1 length? n2 [return to string! (to integer! 
 n1) + to integer! n2]

 if 0 = len: min 9 min length? n1 length? n2 [return either empty? 
 n1 [n2][n1]]
	a: cp/part n1 (length? n1) - len
	b: at n1 (length? n1) - len + 1
	c: cp/part n2 (length? n2) - len
	d: at n2 (length? n2) - len + 1
	res: add b d
	tmp: add a c

 either len < length? res [tmp: add tmp "1" remove res][insert/dup 
 res "0" len - length? res]
	append tmp res
]
[/code]

2
johnsjvi95
24-May-2021 3:31

I am a begginer in this field and I am having a hard time in doing some scripts. Thank you for sharing this.

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It works for me too. Thank you.

It really works. Thank you.

I appreciate the wonderful information. I hope that there's more to come.

The big number is rebuild by addition and concatenation of intermediate results.

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Hello! It's great to hear that you've reviewed the script and found it functional, but you're right that there may be more efficient algorithms out there for performing multiplication and addition of large numbers.

The code you've provided is implementing a recursive approach to decomposing the numbers into smaller pieces that can be handled natively by Rebol. This is a common technique used in large number arithmetic, and can certainly be more efficient than straightforward long multiplication or addition algorithms.

However, it's worth noting that there are many existing libraries and modules for handling large number arithmetic in a variety of programming languages, which may be more efficient and thoroughly tested than rolling your own implementation.

That being said, if you're interested in exploring more efficient algorithms for large-number arithmetic, I would recommend starting with some research into the Karatsuba algorithm and the Toom-Cook algorithm. These are both widely-used techniques for multiplying large numbers that can be more efficient than traditional long multiplication.

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MakeDoc2 by REBOL- 1-Apr-2023

24
madelsmith
5-Apr 5:39

Thank you for the suggestion! However, I would like to clarify that the code I provided was not intended to be an optimized solution for multiplication, but rather a simple example of how to implement a multiplication function using recursion in Python.

Discussion posts for script bignumbers.r

I am a begginer in this field and I am having a hard time in doing some scripts. Thank you for sharing this.

Contents:

free guest posting sites list

Contents:

Love this post. Thank you. Painting services Santa Rosa

Contents:

It works for me too. Thank you.

Contents:

It really works. Thank you.

Contents:

I appreciate the wonderful information. I hope that there's more to come.

Contents:

The big number is rebuild by addition and concatenation of intermediate results.

Contents:

Nowadays, searching on the internet for better codes is also a good thing. The learning never stops. :)

Contents:

It's nice to see this awesome post here. tile cleaning west jordan ut

Contents:

We are here to meet whatever requirements you may need for the type of event you have.

Contents:

Very much appreciated that you take the time to share this with us. Cincinnati SEO agency

Contents:

We also offer many different services, including semi truck engine repair, commercial truck suspension repair, air conditioning service, semi trick air brake service, and many more.

Contents:

If you're getting a NA result from the preceding line, turning off scientific notation may help spin the wheel. The command to use for this is "base options."

Contents:

Ficode Technologies Limited is a leading software development company in the United Kingdom focused on delivering best custom website development servicesto our customers.

Contents:

We understand the importance of keeping your truck running smoothly, so we’ll work diligently to get your truck back on the road as soon as possible.

Contents:

We are dedicated to keeping your car on the road and running smoothly, and we will always go above and beyond to make sure you are satisfied with the work we do.

Contents:

We also offer emergency brake repairs.

Contents:

Hello! It's great to hear that you've reviewed the script and found it functional, but you're right that there may be more efficient algorithms out there for performing multiplication and addition of large numbers.

Contents:

Thank you for the suggestion! However, I would like to clarify that the code I provided was not intended to be an optimized solution for multiplication, but rather a simple example of how to implement a multiplication function using recursion in Python.

Contents: