Error in evaluating an inverse Matrix

[vlehner]

Hi,

When evaluating the inverse Matrix of A, i got two different results in MP4 using the symbolical evaluation and the evaluation with "=".

Creating the same inverse Matrix in MC15 does give the same correct results by evaluating the same way like above.

Has somebody the same experience when calculating Matrices in Prime?

See attachement please.

[ValeryOchkov]

I think it is a bug in Mathcad Prime 4!

[ValeryOchkov]

All OK in Mathcad 15

[Werner_E · Accepted solution]

I can't open your file and just gave it a try with Prime 3.0.

Here all ist OK as it should be.

Only if I set the math format to "Decimal" with 0 decimals displayed, I get the result seen in Valery's pictures.

So unless you accidentally used that misleading setting in your sheet, its definitely a severe bug introduced after P30.

What do you get if you evaluate A*A^-1= ? If you still get the identity, its just a display probem, otherwise its an even more fatal bug.

[ValeryOchkov]

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@WernerExinger wrote:

I can't open your file and just gave it a try with Prime 3.0.

But I can - it is for my Mathcad Mad House!

 

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[vlehner]

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@WernerExinger wrote:

So unless you accidentally used that misleading setting in your sheet, its definitely a severe bug introduced

What do you get if you evaluate A*A^-1= ? If you still get the identity, its just a display probem, otherwise its an even more fatal bug.

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That's it!

It's not a bug, it was my careless of the setting of the displayment of numbers.

if i set the display to 3 decimals all is ok.

Passt!

Thanks Werner.

[ValeryOchkov]

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@vlehner wrote:

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@WernerExinger wrote:

So unless you accidentally used that misleading setting in your sheet, its definitely a severe bug introduced

What do you get if you evaluate A*A^-1= ? If you still get the identity, its just a display probem, otherwise its an even more fatal bug.

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That's it!

It's not a bug, it was my careless of the setting of the displayment of numbers.

if i set the display to 3 decimals all is ok.

Passt!

Thanks Werner.

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We say in this case: "И на старуху бывает проруха!" 

[vlehner]

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@ValeryOchkov wrote:

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We say in this case: "И на старуху бывает проруха!" 

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Good old Google translator says: "Und die alte Frau ist proruha"

[Werner_E]

OK, so this time we can't blame Prime  🙂

[vlehner]

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@WernerExinger wrote:

OK, so this time we can't blame Prime  🙂

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it's sometimes tricky with the settings, especially when copying files and changing them.