get_input returning in different value/units than specified

[ssp-hank]

Thanks for building and sharing this.

I have an issue with inputs returning in units other than what I have designated in my file.

[MattWoodhead]

Hi there.

You are welcome, it is always nice to find out people are actually finding a use for it!

I have set up this simple test case (with the MathCAD unit system set to USCS):

You can do the following (note the addition of the "units" argument in the second function call):

To get this result:

I appreciate this isn't very helpful if you do not know the units of the output ahead of time, but it might get you closer to what you are looking for if you werent already aware that you could do the above.
I will look into the API documentation to see if there is any way of extracting the units as they are entered in the worksheet, rather than converted back to the base units system set in the Math tab.

[ssp-hank]

Oh I definitely have a use for it once I can get it rolling! I'm not an end user of MathCad, just a programmer trying to automate engineering tasks.

So my issue is more on the input side. The data I have coming to me is in ft*kips and I want to feed that straight into the mathcad ws from mysql.

So right now in the file its set to 8.9 ft*kips and if i just return that it converts it which should be ok for the rest of the file to calculate.

When I set it, it just puts that value as 'lb*ft^(2)*s^(-2)' with no conversion. Obviously going to give me the wrong results.

[MattWoodhead]

Ah I see, apologies for misinterpreting the question.

The function call for set real input is as follows:
.set_real_input(input_alias, value, units="", preserve_worksheet_units=True), so if you all the function with units="ft*kip", this should set the correct value (I am not sure if it will convert it to "lb*ft^(2)*s^(-2)" in the process, I will check later).
The preserve_worksheet_units=True argument will cause the set_real_input function to raise an exception if you try to set an input to different units than it is already set in the file, unless you set preserve_worksheet_units=False

I will try this later today, but feel free to give it a go and let me know how you get on.

[ssp-hank]

For some reason the preserve worksheet units is defaulting to "lbft^(2)s^(-2)", even though my ws has ftkip.
I was able to pass the input with by turning the preserve units to false and passing along ftkips, though.

I seem to be making progress this afternoon with this info, thanks!

[MattWoodhead]

I think we must have been giving this a go at around the same time. To address my earlier uncertainty, the display in MathCAD does at least remain in ft*kip if that is what you send it in (and the value is correct too). As you have noted, Mathcad still considers this to be a value in lb*ft^(2)*s^(-2), so the preserve_worksheet_units argument must be False.

It think this is because the conventional units of ftkip are being converted internally into what MathCAD determines to be the base units of the USCS - You can view this by querying the default display of any object with its value set in ftkip:

The preserve_worksheet_units argument is not part of the MathCAD API, it was something I added to the MathcadPy wrapper to make sure people (including me!) remembered that they needed to be careful about what they were sending the API.

I havent been able to locate any functions in the API to extract the units of the worksheet as displayed, so I shall add a warning about this behaviour in the docs.