Inverse Matrix

[Lin Su]

Hi = )!

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

what am i doing wrong?

[salvomic]

(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), there`s 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

[Joe Horn]

(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), there`s 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), there`s 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?

[DrD]

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-

[Lin Su]

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!

[salvomic]

(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!

never mind, we are glad to help you!
:-)

ciao