Inverse Matrix
06-28-2015, 05:01 AM (This post was last modified: 06-28-2015 05:02 AM by Lin Su.)
Post: #1
 Lin Su Junior Member Posts: 4 Joined: Jun 2015
Inverse Matrix
Hi = )!

When i calculate the inverse matrix, i use inv(Matrix) and for small numbers(img.1), theres no problem but when i try to calculate using large number(img.2)..it shows wrong result..

what am i doing wrong?

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06-28-2015, 06:27 AM
Post: #2
 salvomic Senior Member Posts: 1,394 Joined: Jan 2015
RE: Inverse Matrix
(06-28-2015 05:01 AM)Lin Su Wrote:  Hi = )!

When i calculate the inverse matrix, i use inv(Matrix) and for small numbers(img.1), theres no problem but when i try to calculate using large number(img.2)..it shows wrong result..

what am i doing wrong?

large number is the image (2?) with [[4,5][6,7]]?
its inverse is [[-3.5,2.5][3,-2]], correct.
Or am I missing something?

Salvo

∫aL√0mic (IT9CLU) :: HP Prime 50g 41CX 71b 42s 39s 35s 12C 15C - DM42, DM41X - WP34s Prime Soft. Lib
06-28-2015, 08:17 AM
Post: #3
 Joe Horn Senior Member Posts: 1,873 Joined: Dec 2013
RE: Inverse Matrix
(06-28-2015 05:01 AM)Lin Su Wrote:  Hi = )!

When i calculate the inverse matrix, i use inv(Matrix) and for small numbers(img.1), theres no problem but when i try to calculate using large number(img.2)..it shows wrong result..

what am i doing wrong?

(06-28-2015 06:27 AM)salvomic Wrote:
(06-28-2015 05:01 AM)Lin Su Wrote:  Hi = )!

When i calculate the inverse matrix, i use inv(Matrix) and for small numbers(img.1), theres no problem but when i try to calculate using large number(img.2)..it shows wrong result..

what am i doing wrong?

large number is the image (2?) with [[4,5][6,7]]?
its inverse is [[-3.5,2.5][3,-2]], correct.
Or am I missing something?

Salvo

The images are displayed on the forum web page in reverse order. By "img.2" he means the image on the left.

Lin: I typed your 5×5 matrix into my Prime, and it gets the correct inverse both in Home and in CAS. Could there be a typo in your input?

<0|ɸ|0>
-Joe-
06-28-2015, 09:17 AM
Post: #4
 DrD Senior Member Posts: 1,132 Joined: Feb 2014
RE: Inverse Matrix
With the Excel matrix entered into M6, my results agree with Joe's, (I get the correct inverted values). Just for fun, notice the precision difference between inv(inv(M6)) function value, and (M6^-1)^-1.

Using the exponential form returns the original M6, while the inv() function returns a little less precision.

-Dale-
06-29-2015, 10:28 PM
Post: #5
 Lin Su Junior Member Posts: 4 Joined: Jun 2015
RE: Inverse Matrix
Hi Again X)

Thanks !! it was my typing mistake. You were right!!! . Salvomic, Joe Horn, DrD.. For give me for "stealing" your time = ( and Thanks again!
06-29-2015, 10:33 PM
Post: #6
 salvomic Senior Member Posts: 1,394 Joined: Jan 2015
RE: Inverse Matrix
(06-29-2015 10:28 PM)Lin Su Wrote:  Hi Again X)

Thanks !! it was my typing mistake. You were right!!! . Salvomic, Joe Horn, DrD.. For give me for "stealing" your time = ( and Thanks again!