Wrong behaviour in logarithmic plots?

[CH_10552914]

Hello,

my Company forces me to switch from MathCAD15 to prime 10. Despite many other item I have question about logarithmic plots:

How can I set that the break points for calculation are also done on a logarithmic base?

It seems that the brake points still have linear steps --> almost no resolution on the low value end - even when setting "Number of Points" to 3000.

[LucMeekes]

Hi,

Welcome to this forum.

1. Please attach the (Prime) worksheet.

2. Did you define Rs? If yes: How is it defined?

Success!
Luc

[Werner_E]

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@CH_10552914 wrote:

Hello,

my Company forces me to switch from MathCAD15 to prime 10.

My condolences to you!

I can confirm that in Prime the quickplot feature (plotting without defining the abscissa variable) with a logarithmic ordinate axis is broken.
As you already suspected, the values still are spaced linear which is unusable.

Mathcad 15:

The same in Prime 10 (using the default 500 points):

A possible way around this bug could be to define the ordinate values as a vector with logarithmically spaced values created with "logspace".

Here again using 500 points:

Vectorization (the arrow over the expression) is not mandatory in case of the function f used here but may be needed for other functions. So I consider it a good idea to use explicit vectorization every time you feed a vector as argument in a function written for scalar arguments.

BTW, I notice that the picture of the MC15 plot you attached showed a plot using a secondary y-axis. Primes native plots do not provide a secondary y-axis (and no labels and no grid lines ...). PTC therefore, instead of improving the native plots, had integrated a third party tool ("Chart component") which has a second y-axis, labels, gridlines, but also its own drawbacks - apart from being really slow it does not know anything about units. If the secondary y-axis is mandatory you would have to use that Chart component to create the plot.

[CH_10552914 · Accepted solution]

Hello Werner,

thanks a lot for your supply. Your workaround can be a solution.

2nd y-axis are often required, especially if the values of the 2 graphs differ too much. On bode plots it works with one axis, but what if you have Volts and Milliamps?

Seems I need to try the "Chart Component" - or a different mathematical tool...

BR Christoph

[ttokoro]

If each plot has different unit, you can plot all in one plot. 

[Werner_E]

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@CH_10552914 wrote:

Hello Werner,

thanks a lot for your supply. Your workaround can be a solution.

2nd y-axis are often required, especially if the values of the 2 graphs differ too much. On bode plots it works with one axis, but what if you have Volts and Milliamps?

Seems I need to try the "Chart Component" - or a different mathematical tool...

BR Christoph

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Different units in one plot are no problem but different magnitudes of values can be and may require a secondary y-axis or ... simply a second, separate plot. Most of the times showing the two traces in one plot has the only benefit of saving space and so its not a big loss to invest in separate plots.

I usually prefer separate plots because I find plots with a secondary y-axis harder to read and comprehend.