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8-Gravel

## Piecewise function plot

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

1 ACCEPTED SOLUTION

Accepted Solutions
23-Emerald III
(To:ebelmonte)

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

7 REPLIES 7
23-Emerald III
(To:ebelmonte)

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

8-Gravel
(To:LucMeekes)

Dear Luc,

Attached you find the file in .mcd format.

23-Emerald III
(To:ebelmonte)

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

23-Emerald I
(To:ebelmonte)

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

23-Emerald III
(To:Fred_Kohlhepp)

Where?

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

Luc

21-Topaz II
(To:ebelmonte)

Salve,

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

23-Emerald III
(To:-MFra-)

Buona giornata,

Ecco di cosa si occupa la vettorializzazione.

Successo!
Luc

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