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1 ft Not Equal to 12 in

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1 ft Not Equal to 12 in

I have noticed that both in the older versions of Mathcad, as well as the new Prime versions, there is an issue when using both feet and inches units in a worksheet.  It appears that in mathcad 1 ft is not exactly equal to 12 in (if you evaluate ft = 12in, the return vaule is 0).  I am assuming that this is a result of 1in being equal to 0.08333333333 ft.  This can become an issue when using the rounding functions when things are evenly divisible.  For example, 10 ft / 12in calculates to 10.000000000000002.  If you were to evaluate  ceil(10ft / 12in) the result would be 11 NOT 10.  Is there any way to resolve the internal threshold/rounding issue? 

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Re: 1 ft Not Equal to 12 in

In Mathcad 15, go to "Tools", "Worksheet options", the "Calculation" tab, and uncheck "Use exact equality for comparisons and truncation". In Prime go to the "Calculation" tab, and select "Approximate equality" under "Calculation options".

 

I have this set this way in my default document template.

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Re: 1 ft Not Equal to 12 in

In Mathcad 15, go to "Tools", "Worksheet options", the "Calculation" tab, and uncheck "Use exact equality for comparisons and truncation". In Prime go to the "Calculation" tab, and select "Approximate equality" under "Calculation options".

 

I have this set this way in my default document template.

View solution in original post

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Re: 1 ft Not Equal to 12 in

Thank you Richard!  This solved the issue.  I am just surprised that Mathcad doesn't handle these units better and that there is not some internal rounding/tolerance done to prevent this.  Thank you for the answer!

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