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ebelmonte1-Visitor
1-Visitor
October 30, 2019
Solved

Piecewise function plot

Dear Mathcad community,

 

I have a problem when plotting a piecewise function.

The error is "all evaluations resulted in either an error or a complex result".

I would really appreciate if anyone can help me!

 

Thank-you very much.

 

Best Regards.


Enrico

LucMeekesAnswer
23-Emerald IV
October 30, 2019

The evaluation of:

F.input_rod(a)=

results in an error message "Must be scalar".

Tracing further back I find that in your definition of F.input_rod(a) you are comparing a with 10 m/s^2.

Note that a is an array, you cannot compare an array with a scalar value.

Your way out is simple: vectorize the F.input_rod(a) so that the function acts on each value, but still produces all results.

See attached.

 

Success!
Luc

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7 replies

LucMeekes23-Emerald IV
23-Emerald IV
October 30, 2019

Can't see your sheet, unless you save as Mathcad 11..

 

Here's some advice to help you debug:

Evaluate the variable you want to plot. If you plot e.g. y(x) and have x defined (either as a range variable or as a vector), type

    y(x)=

and

    x=

To see the value(s) each has. There may be NaN's in there, or imaginary numbers. Or another error occurs.

In case of an error, select the evaluation and, using the righthand mouse button, select 'trace error', and trace that error back to where it occurs.

 

Success!
Luc

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ebelmonte1-VisitorAuthor
1-Visitor
October 30, 2019

Dear Luc,

Thank-you for your reply.

Attached you find the file in .mcd format.

 

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LucMeekes23-Emerald IVAnswer
23-Emerald IV
October 30, 2019

The evaluation of:

F.input_rod(a)=

results in an error message "Must be scalar".

Tracing further back I find that in your definition of F.input_rod(a) you are comparing a with 10 m/s^2.

Note that a is an array, you cannot compare an array with a scalar value.

Your way out is simple: vectorize the F.input_rod(a) so that the function acts on each value, but still produces all results.

See attached.

 

Success!
Luc

Translate
    Fred_Kohlhepp23-Emerald I
    23-Emerald I
    October 30, 2019

    Just a quick look (in Smath), you have some unit balance issues.

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    LucMeekes23-Emerald IV
    23-Emerald IV
    October 30, 2019

    Where?

    I don't see them. Mathcad (11) also not.

     

    Luc

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    -MFra-21-Topaz II
    21-Topaz II
    October 30, 2019

    Salve,

    non puoi confrontare il vettore a con uno scalare. Il confronto con lo scalare va fatto elemento per elemento .

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    LucMeekes23-Emerald IV
    23-Emerald IV
    October 30, 2019

    Buona giornata,

    Ecco di cosa si occupa la vettorializzazione.

     

    Successo!
    Luc

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