Ventana software support forum

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...

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...

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.

Thank you for the answer. It seems you understood quite clearly what I was asking.

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...

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...

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.

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!

Thank worked, thank you!
Looks like...
SAMPLE IF TRUE( LMTD>max LMTD, LMTD, LMTD)

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...

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!

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...

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 ...

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 ...

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...

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...

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:

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.

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. ...

@tomfid, do you know which would be computationally faster? Would it be the iterative solve with FIND ZERO or the LOOKUP?

This (FIND ZERO) worked perfectly. Thank you.

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],...

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...

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...

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...