Vector limiting value

[mar2805]

Guys Im wondering if you could help me a bit.
If you could open the file attached.
I defined a vector wich goes from 0-1000mm with delta=1mm.
Problem is that I have a formula in my sheet that should use for x, as a final value, infinity.
I tried enlarging the limiting value for x, wich is 1000mm to some BIG number but every time I get above 100000, Mathcad craches.
Can this be due to small amount of memory (4GB)?

Is there any chance that this vector can also have the infinity as the last value?
Thank you

 

[IRstuff]

Perhaps, again, you should describe what you want to accomplish. You are listed as structural, so where on earth can you physically find an infinite length of millimeters?

In any case, there is no problem with defining y.end up to about 10E7. But the notion that one needs 1-mm resolution over a 10km does not make sense.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[mar2805]

"In any case, there is no problem with defining y.end up to about 10E7"
Is this interpreted as infinity in Mathcad or not?

Do you have any problems with Mathcad crashing when operating with so large values?

 

[IRstuff]

No, because, there is rarely a need for such a construct. 10E7 is 10 million times larger than your smallest increment, which may, or may not, be effectively, infinity.

How can you possibly expect a plausible answer without any context?

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[mar2805]

IRstuff,
I dont Know if you have downloaded my project that Ive uploaded last month, when you said that it was an "homework" attempt, but if you have you can basicly see that there is an value called x at the begining wich you can set from 0mm to infinity.
The whole project has been set up with vectors now and it works.
x is defined as a vector in my previous attach
The only problem remaninig is how to account for a value - infinity.
Becasue when x=infinty the 2 M values become 0 (zero).
I could use as you mentioned an large value for like 10E7 but that doesnt give 0 to my 2 M values.
They are very very close to it, something like 0,05
Maybe to use the rounding function in these situation wich would round those small values to ZERO.

Again, did you experienced any troubles when using so BIG ranges?
Did Mathcad crashed?

 

[structSU10]

big ranges with a very fine (relative to its size) defined increment will be taxing on the system, especially if you are trying to graph it. I cannot open you Mathcad as I am on a much older version, but listen to IRstuff - when is infinity ever needed in reality? What are you trying to accomplish that would include an infinite value (especially a length)? There must be some way to bound it to something more reasonable. Do you need to have the equation have an increment of 1mm or can that be enlarged? If you use a larger value for that you can use a larger number for the range with potentially less issues. If you explain what you are trying to accomplish it may help us to help you.

 

[IRstuff]

"Again, did you experienced any troubles when using so BIG ranges?
Did Mathcad crashed?"

Your question was answered in my first post, and no, Mathcad did not crash.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[mar2805]

You havea point there.
It might my wise to enlarge the increment value, but in that way I might get in situation where Im loosing some of the important points (values).
Is there any way that besides defining a range of values (wich almost always follow a sequence) you can define Extra few values that are of great importance (but are unfortunatly going to be skipped using a sequence)

@struct
Im contoling the position of the neutal axis of a cross section. SO when n.a. is at infinity you have a section in pure tennsion or compression. Moments are ZERO! Important value wich I dont Know how to include.

 

[IRstuff]

"where Im loosing some of the important points (values)."

Again, where would you actually need an infinite number of millimeters? You have nothing in your original problem that would have that; if you do, then you need to figure out how to get around that.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[mar2805]

Im sorry but I dont understand what your saying.
Can you explain your solution/advice regarding my previous post where I said that infinity is an important vlaue that should be an end part of a sequence.
Thank you.

 

[IRstuff]

Presumably, your original problem has some physical basis in reality. The fact that you are looking for an infinitely large parameter for this problem demonstrates that the form of parameter was poorly chosen. For example, you could have possibly chosen a particular angle, instead of whatever you think requires an infinite number of millimeters, and the table would be drastically reduced. The fact that you need an infinitely large distance to map into a 2-meter distance says also shows that. Even if you picked millimeters in the 2-meter distance to express the table, there would only be 2000 entries, and they would all be physically meaningful.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[mar2805]

Is there any way that besides defining a range of values (wich almost always follow a sequence) you can define Extra few values that are of great importance (but are unfortunatly going to be skipped using a sequence).
Or maybe just define few values that dont follow any particular sequence?

 

[IRstuff]

Your other choice is to fill in a vector with arbitrary values of your own choosing

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[mar2805]

This sound interesting.
Can you provide an egsample, please.

 

[IRstuff]

There are a number of possibilities
> Type <CTRL>+m to insert a matrix, change the rows and columns as needed
> Insert an Excel worksheet
> Insert a data entry table
> Use an algorithm to generate the desired values

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[mar2805]

Wich one do you prefer and since I already have everthing set for calculating with vectors, wich one would you recommend.
Thank you.

 

[IRstuff]

It doesn't matter to me; they all result in a vector of numbers.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[jghrist]

From Mathcad Help:

The array size limit depends on the memory available on your system. Approximately 8 bytes of memory are needed per array element. For most systems, the array limit is at least 1 million elements. Note that the maximum allocatable memory in a 32 bit system is 4 Gb, which has to hold all open applications, your operating system, and whatever memory is consumed by your calculations.

You can set the zero threshold with Format|Result|Tolerance|Zero Threshold. If set at 15, then numbers smaller than 1E-15 show up as zero.