I was playing around with sorting and decided (yet again) that I was frustrated by some of the restrictions. One thing led to another, and before I knew it, I was hip deep in ways to "improve" the lookup functions.
While contemplating Mathcad Zen Principles 3, 6, 7, 16, and 17, I wondered whether "unique" would be a worthwhile addition to the match/lookup modifiers.
Then my mind went blank when faced with how to handle NaNs. In principle, IEEE 754 NaNs are distinct. And they would be if a standard Mathcad user had any way to distinguish between them, but they're harder to tell apart than Zathras and Zathras. To the Mathcadder in the street, they might as well be indistinguishable, for all the good their distinctiveness does.
So, I've written two versions of unique to cater for both cases. The question is which one would a user expect to be the default (and hence all lowercase) version?
I've checked in a few other languages. Matlab seems to be an outlier in treating NaNs as distinct. Python (numpy), Julia, and (surprisingly) Mathematica appear to treat NaNs as indistinguishable from each other (for uniqueness testing); even XCas does so: set( [1,2,4,5,NaN, 6,2,NaN,5,1,4,2,5]) == 1,2,4,5,NaN,6
.
In the meantime, could a kind soul please check whether the attached Mathcad Express 10.0 worksheet works in Mathcad Prime?
I'd expect the results to look something like this:
Thank you,
Stuart
https://www.validlab.com/goldberg/paper.pdf
https://community.ptc.com/t5/Mathcad/MEP-00-The-Zen-of-Mathcad/m-p/1040983#M219315
3. Be like Zathras-- cover all possibilities. Zathras does not want other people being confoosed.
6. Explicit is better than implicit.
7. Unless implicit is better.
16. Functions should work over any data type.
17. Except where there is no meaning.
The function trim() operates as follows:
So it doesn't throw out the 3 AND the 4, only the 3.
See attached. Also observe what happens when you change ORIGIN (before all function definitions of course).
Success!
Luc
The same goes for the built-in "trim" function
Is the repeated use of an index also known as "secure erase", just like the repeated overwriting when you're wiping hard drive data?
If the index is used once, the row is gone. If you repeat the index, the row is goner ? 😉
That's why my trim() function was built the way it was. It is supposed to implement the functionality of the trim() function in full Prime.
After posting I realised that my trim() has a built-in unique() functionality (to make sure that the same index isn't used twice). It is:
(the operating function in the fold is called 'set_fold' because it makes a vector into a mathematical set, one in which each element value occurs only once)
So with that I can build:
with as results on M, N and N2:
"If the index is used once, the row is gone. If you repeat the index, the row is goner ? "
If you carelessly repeat the index, the corresponding position in the vector and an adjacent one could be deleted.
But it's an interesting idea to have an Array that remembers the values of each of its members, especially if it also administrates what action, executed by which function, made an element value change, and when it happened...Secure array management!
Success!
Luc
When you define "match" and "Match" you have to decide whether the formal argument name should be "x" or "z" 🙂
And function "_eq" is not defined, only "eq" and of course "_eqNaN".
Later in your sheet you use both "eq" and "_eq".
BTW, I sometimes found it annoying that Prime treats NaN with units differently from "normal" unit-less NaN's which made it necessary in some programs to add units to NaN's. Nonetheless the "IsNaN" functions seems to not care about the units.
That's definitely a difference in behaviour compared to Mathcad.
Prime 11.0.0.0:
Mathcad 15:
