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03-29-2011
03:10 PM

03-29-2011
03:10 PM

Mathcad without range variables

Programming without GOTO statements - it is possible (a discussion of 30 years ago).

Mathcad without range variables - is it possible?

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03-29-2011
03:23 PM

03-29-2011
03:23 PM

Re: Mathcad without range variables

Why get rid of them and not just ignor them?

Mike

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03-29-2011
06:52 PM

03-29-2011
06:52 PM

Re: Mathcad without range variables

Matlab manages without them, but that doesn't make it right.

We need horses for courses.

We also need dimensional indexing as well, e.g. if you have a beam, you should be able to get at the result's vector for location r=0.5m, not just have to access at index=20 (or what ever step size was used)

Philip

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03-30-2011
02:26 PM

03-30-2011
02:26 PM

Re: Mathcad without range variables

We also need dimensional indexing as well, e.g. if you have a beam, you should be able to get at the result's vector for location r=0.5m, not just have to access at index=20 (or what ever step size was used)

Yes, this does need to be implemented. Have you requested this before?

Mike

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03-30-2011
03:15 PM

03-30-2011
03:15 PM

Re: Mathcad without range variables

Mike Armstrong wrote:

We also need dimensional indexing as well, e.g. if you have a beam, you should be able to get at the result's vector for location r=0.5m, not just have to access at index=20 (or what ever step size was used)Yes, this does need to be implemented. Have you requested this before?

Mike

Yes, I've suggested it on the old collaboratory. One particular area I'd like it for is fft() and FFT() which could then get the right units for the frequency spacing and the amplitude units in the two cases e.g. for a voltage sequence in time.

One of the FFTs is for noise density (e.g. Volts per root Hz), and the other is for spot frequency amplitudes(volts). The time axis also becomes a frequency axis.

The discussion at the time also focused on the 'nearest' problem that match and comparisons have, along with choices about what sort of interpolation should be allowed if the index doesn't point to a particular sample of the vector.

Philip

Message was edited by: Philip Oakley. PS there is a simple way to decide if the index must be an integer or is a 'float', and that is the presence of dimensions, whether those are SI dimensions or off-system ones [Currency being an obvious off-SI-system dimension]

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03-30-2011
03:34 PM

03-30-2011
03:34 PM

Re: Mathcad without range variables

The discussion at the time also focused on the 'nearest' problem that match and comparisons have, along with choices about what sort of interpolation should be allowed if the index doesn't point to a particular sample of the vector.

Have you got Mathcad 15? There is a feature which will allow the Match function to return the closet match, if an exact match is not found.

Message was edited by: Philip Oakley. PS there is a simple way to decide if the index must be an integer or is a 'float', and that is the presence of dimensions, whether those are SI dimensions or off-system ones [Currency being an obvious off-SI-system dimension]

I love the way Mathcad handles units, but you have defiantly found a flaw which should be addressed. I also think we should have a function UnitOf() which will keep track of the unit the way it is defined at sheet level, not convert it to SI units.

Mike

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03-31-2011
12:41 AM

03-31-2011
12:41 AM

Re: Mathcad without range variables

Valery Ochkov wrote:

Programming without GOTO statements - it is possible (a discussion of 30 years ago).

Mathcad without range variables - is it possible?

More specific question.

Can we remove range variables from any (each) calculation?

I do not ask why.

I ask, can.

I know a lot of calculations, where range variables and vectors are in conflict and where better to retain only the vectors.

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03-31-2011
03:12 PM

03-31-2011
03:12 PM

Re: Mathcad without range variables

I know a lot of calculations, where range variables and vectors are in conflict and where better to retain only the vectors.

I fully agree with this and try and keep away from running calculations with range variables.

Mike

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03-31-2011
05:21 PM

03-31-2011
05:21 PM

Re: Mathcad without range variables

I am not sure what you are getting at,

But I (like Mike) use range variables to construct vectors, like x[i, so Phillps comment about moment at point on a beam, is never a function of a range variable, only of x. Actually, to keep straight for myself, when I want a vector of x values, I use xx[i, so I can use both M(x) and MM(xx) or MM[i=M(xx[i) so I don't screw one or the other up.

Is this what you are talking about?

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04-01-2011
07:36 AM

04-01-2011
07:36 AM

Re: Mathcad without range variables

What's wrong with the lookup function?