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08-03-2018
07:02 AM

08-03-2018
07:02 AM

Hello Everyone,

I am an electronics engineer who has just started with Mathcad v15. I work on a sheet which calculates total power dissipation in a power supply. I have many input variables which help me to get the desired information - total power dissipation (**Ptot**) and predicted efficiency (Eff). So far, the calculation sheet works well.

**The struggle:**

Now, I would like to vary some input parameters and see in a plot how total efficiency change. For example, I want a plot with **Iout** on the x-axis and **Eff** on the y-axis. I have already spent half a day by googling but could not come up with a solution. Could someone review the sheet and come with a proposal how to make a **Eff** vs **Iout** plot, please? I expect that I need to somehow turn my equation into a function (numerical vs symbolic engine).

PS: A tip what to search on the forum will do too.I am not lazy :-)

Best Regards, Jiri

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08-03-2018
08:28 AM

9 REPLIES

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08-03-2018
08:28 AM

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08-03-2018
08:31 AM

08-03-2018
08:31 AM

The best way is to make sure that your Eff calculation is a function of Iout, then you can plot it.

Here's an example:

Success!

Luc

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08-03-2018
08:37 AM

08-03-2018
08:37 AM

Unfortunately Mathcad does not offer a way to turn a worksheet into a function automatically (a long standing wish).

So what you have to do is to create the functions yourself.

Every calculation which uses one of the input variables you would like to change later has to be turned into a function dependent on those inputs.

Here is a simple example. Instead of a static calculation of just one value

you turn the calculations into functions

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08-03-2018
08:39 AM

08-03-2018
08:39 AM

Alan, this is great! What is the name of the magic you did with "k"? I understand how it works but I would like to study it more.

Thank you for your help and efforts.

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08-03-2018
08:47 AM

08-03-2018
08:47 AM

@Werner_E, @LucMeekes: I see... This is probably what I need to do. However, the resulting function is going to be super long because I want to play practically with all parameters.

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08-03-2018
08:47 AM

08-03-2018
08:47 AM

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08-03-2018
08:50 AM

08-03-2018
08:50 AM

Or, as Luc suggests, using functions

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08-03-2018
10:00 AM

08-03-2018
10:00 AM

@Jip wrote:

Yes, thats the drawback when we are dealing with more complicated calculations.

Unfortunately other than using abbrevations for some functions there seems to be no other option.

Unless of course Alans solution using vectors for all calculations is sufficient.

Thats why many people have worksheets which can be turned into a function which could be used as such in a second worksheet on their wishlist.

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08-03-2018
03:26 PM

08-03-2018
03:26 PM

k is a range variable. You can find out about them in the help facilities.

Alan

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