Search found 46 matches
- Sun Apr 21, 2024 1:17 am
- Forum: Vensim
- Topic: Death by Subscript
- Replies: 5
- Views: 117
Re: Death by Subscript
I need to counter this by asking what the SUM() function is. It does not appear that it is a large operator, upper case sigma. If it was, it would not need subscripts at all. h does nothing. It is a formality in an attempt to get SUM() to work like a sum. In the manual and in the program I cannot si...
- Sat Apr 20, 2024 10:30 pm
- Forum: Vensim
- Topic: Death by Subscript
- Replies: 5
- Views: 117
Death by Subscript
Hi, As usual, I have no idea where to find coherent documentation on subscripts in the Vensim manual. I am trying to use the SUM() function for the equation shown. Pretty straightforward in reality. In Vensim it is like pulling teeth. picture.png Shown is what I have input into the variable: picture...
- Tue Apr 16, 2024 3:41 pm
- Forum: Vensim
- Topic: SINTEG with vars
- Replies: 4
- Views: 105
Re: SINTEG with vars
The problem with the help file stating: "The remaining arguments must all be numbers." is that the variable inputs are numbers. Fine though Admin, I get it. Thank you.
- Tue Apr 16, 2024 3:35 pm
- Forum: Vensim
- Topic: Integration techniques: Impacts on Stock behavior
- Replies: 5
- Views: 190
Re: Integration techniques: Impacts on Stock behavior
Thank you for the answer. It seems you understood quite clearly what I was asking.
- Mon Apr 15, 2024 11:15 pm
- Forum: Vensim
- Topic: Integration techniques: Impacts on Stock behavior
- Replies: 5
- Views: 190
Re: Integration techniques: Impacts on Stock behavior
I am not sure that this is impossible to answer. I am not asking anything about my model. Rather, why are the different integration techniques not affecting behavior at the same time step? The signal is entirely the same, offering a control which indicates the only problems are the integration techn...
- Sun Apr 14, 2024 10:41 pm
- Forum: Vensim
- Topic: Integration techniques: Impacts on Stock behavior
- Replies: 5
- Views: 190
Integration techniques: Impacts on Stock behavior
Hi, I recently switched my integration technique on an hourly simulation to RK2Auto. After looking more closely at the impacts on the model, I found significant errors. I understand that the RK methods are basically midpoint Euler steps, but I wonder why they are forcing a delay in integration withi...
- Sun Apr 14, 2024 10:30 pm
- Forum: Vensim
- Topic: SINTEG with vars
- Replies: 4
- Views: 105
Re: SINTEG with vars
It's not a big deal. I switched the function out because SINTEG is a bit unnecessary for what I need to accomplish. For the record, it does not appear that it will take anything but integers in place of min/max.
- Sun Apr 14, 2024 6:14 pm
- Forum: Vensim
- Topic: SINTEG with vars
- Replies: 4
- Views: 105
SINTEG with vars
Hi all,
I am attempting to implement inputs for the SINTEG function. I am trying to assign the min and max values as min=(var1-(var1*.3)) and max=(var1+(var1*.3)). For some reason the SINTEG function does not like using variables as the input for min or max. Is there a workaround to this?
Thank you!
I am attempting to implement inputs for the SINTEG function. I am trying to assign the min and max values as min=(var1-(var1*.3)) and max=(var1+(var1*.3)). For some reason the SINTEG function does not like using variables as the input for min or max. Is there a workaround to this?
Thank you!
- Sat Jan 20, 2024 6:21 pm
- Forum: Vensim
- Topic: Finding MAX of simulation variable
- Replies: 2
- Views: 1184
Re: Finding MAX of simulation variable
Thank worked, thank you!
Looks like...
SAMPLE IF TRUE( LMTD>max LMTD, LMTD, LMTD)
Looks like...
SAMPLE IF TRUE( LMTD>max LMTD, LMTD, LMTD)
- Sun Jan 14, 2024 5:18 pm
- Forum: Vensim
- Topic: Finding MAX of simulation variable
- Replies: 2
- Views: 1184
Finding MAX of simulation variable
Hi all, I am running into this requirement on several simulations. I need to solve for another variable by using the MAX of another variable which may only be found through running of the simulation. VMAX and VMIN appear inappropriate for the case I will show here. I believe it seems appropriate for...
- Sun Jan 07, 2024 5:13 pm
- Forum: Vensim
- Topic: Multi-input Lookup
- Replies: 13
- Views: 30762
Re: Multi-input Lookup
Spot on. This is perfect. Thank you for taking the time on this one.
If nothing else in this long discussion topic, I have become more familiar with subscripts in Vensim. I look forward to that enhancement!
If nothing else in this long discussion topic, I have become more familiar with subscripts in Vensim. I look forward to that enhancement!
- Sat Jan 06, 2024 10:07 pm
- Forum: Vensim
- Topic: Multi-input Lookup
- Replies: 13
- Views: 30762
Re: Multi-input Lookup
I am trying to extract a constant, as in the above table. I do not see how I can explain this very, very simple effort any more clearly. 1. There is a lookup table. It contains inside diameters. 2. There is a pressure number that must be selected because it dictates how thick the pipe needs to be. 3...
- Sat Jan 06, 2024 9:22 pm
- Forum: Vensim
- Topic: Multi-input Lookup
- Replies: 13
- Views: 30762
Re: Multi-input Lookup
This just does not make any sense. According to the example file for the VECTOR LOOKUP, the x, y, values are input to a standardized distribution range of x-min to x-max and y-min to y-max. I, however, input a value of x = 6 and y = 25 which should be "21" in the lookup, but I get 3. This ...
- Sat Jan 06, 2024 8:55 pm
- Forum: Vensim
- Topic: Multi-input Lookup
- Replies: 13
- Views: 30762
Re: Multi-input Lookup
I found one problem in the model. The previously defined variables PN2 - PN16 had lookup tables that were throwing some errors. I deleted those variables and redeclared them as subscripts. Now the model runs. However, the output from lookup is erroneous and appears extrapolated? Not sure. How would ...
- Sat Jan 06, 2024 8:13 pm
- Forum: Vensim
- Topic: Multi-input Lookup
- Replies: 13
- Views: 30762
Re: Multi-input Lookup
Hi JJ, The VECTOR LOOKUP makes sense, sort of. Unfortunately, it does not work either. I am going to layout my attempt at making the VECTOR LOOKUP function work. From the example "VECTOR_LOOKPU.mdl" above. XDim[x1, x2, x3], YDim[y1,y2,y3,y4,y5] 2-dim.png So I set my test problem up as ODDi...
- Fri Jan 05, 2024 5:06 pm
- Forum: Vensim
- Topic: Multi-input Lookup
- Replies: 13
- Views: 30762
Re: Multi-input Lookup
Sorry to hear you are under the weather. I will try to explain this again. This is the order of operations: 1. Pressure number is selected 2. Pressure number limits the pipe diameters. 3. Outside pipe diameter is selected. 4. Based on the selected pressure number and the selected outside diameter th...
- Thu Jan 04, 2024 5:45 pm
- Forum: Vensim
- Topic: Multi-input Lookup
- Replies: 13
- Views: 30762
Re: Multi-input Lookup
Here is the non-ideal workaround I came up with, not knowing how to do the two-dimensional lookup. I add X+Y=Z, then Z=index for lookup, then LOOKUP EXTRAPOLATE(lookup inside diameter, X+Y ). So the lookup appears as:
- Thu Jan 04, 2024 3:42 pm
- Forum: Vensim
- Topic: Solving for implicit functions before starting time
- Replies: 7
- Views: 13561
Re: Solving for implicit functions before starting time
In this case, I think it would be sufficient to assume the tubulars I am working with will not change, but if adding complexity to future production changes this would be a problem. Ok, thank you for the responses.
- Thu Jan 04, 2024 3:17 pm
- Forum: Vensim
- Topic: Multi-input Lookup
- Replies: 13
- Views: 30762
Re: Multi-input Lookup
Thank you for the response. What I am seeing in this example model does not have a selection of the outside diameter. This example is only taking one input and giving one output. I need two inputs, and one output from a lookup table. Again, there are two "selections" that must be made: 1. ...
- Tue Jan 02, 2024 12:58 am
- Forum: Vensim
- Topic: Solving for implicit functions before starting time
- Replies: 7
- Views: 13561
Re: Solving for implicit functions before starting time
@tomfid, do you know which would be computationally faster? Would it be the iterative solve with FIND ZERO or the LOOKUP?
- Tue Jan 02, 2024 12:36 am
- Forum: Vensim
- Topic: Solving for implicit functions before starting time
- Replies: 7
- Views: 13561
Re: Solving for implicit functions before starting time
This (FIND ZERO) worked perfectly. Thank you.
- Mon Jan 01, 2024 11:45 pm
- Forum: Vensim
- Topic: Multi-input Lookup
- Replies: 13
- Views: 30762
Multi-input Lookup
Hi, I am been struggling with this super simple lookup that should work with subscripts. As usual, I cannot make heads or tails of the subscript instructions in the manual for my intended use case. I know, it's just me :roll:. Here is the problem: Inputs: Pressure number [PN16, PN10, PN6, PN4, PN2],...
- Fri Dec 29, 2023 2:37 am
- Forum: Vensim
- Topic: Solving for implicit functions before starting time
- Replies: 7
- Views: 13561
Solving for implicit functions before starting time
Hi, I am trying to run a simulation with the Colebrook equation to solve for the Darcy-Weisbach friction coefficient in a flow problem. This is usually solved numerically with iterations. The trick is that I need to solve for the coefficient before proceeding with the rest of the simulation. Is ther...
- Sat Oct 14, 2023 11:51 pm
- Forum: Vensim
- Topic: Multivariable data lookup and interpolation
- Replies: 1
- Views: 880
Multivariable data lookup and interpolation
Hi, I am trying to import data from a properties spreadsheet for grout mixes. This properties sheet has nothing to do with a timeseries. I believe the correct function to use would be GET XLSX CONSTANTS(). I do not see a way to load this as a .dat or .vdfx because there is no timeseries. Unfortunate...
- Thu Jul 27, 2023 3:29 pm
- Forum: Vensim
- Topic: What improvements would you like to see in Vensim?
- Replies: 150
- Views: 14671450
Re: What improvements would you like to see in Vensim?
I would like to see the new Tornado graph improved, under the Sensitivity2All feature. The outputs are great, but the graph is not a tornado in v10.0.0. Try selecting one of the other measures rather than MAD (such as payoff). This will give you the tornado you are looking for. That was it. Thank y...