V.G Error and Informational Messages

Most of DELTAE's diagnostics are meant to be self-explanatory, but some require additional information. In the following subsections, we offer some additional hints for the more obscure ones.

Convergence errors

These errors occur while DELTAE's solver is iterating during a (r)un:

This is not going well...DeltaE gives up!

Associated with this error will be a message ``info=4", and a listing of the all current guesses followed by all current target - result values. The solver is not able to find an iteration direction that gives improved results. During a plot loop, this error sometimes occurs multiple times, after which the solver once again finds its way. If it persists, a revision to the solution or target vector may be needed, or the starting point (or plot range) may need to be shifted significantly. Examine the .dat file for clues, and think carefully about what is occurring. Simplify the model or iteration if possible. If the error occurs on a model that you know to have good convergence under other conditions, you may be reaching a pathological point. You may be able to jump start it by manually (somewhat intelligently) changing the value of one or two members of the guess vector to put the solver on the right track, or, you may find it very stubborn at this point. Consider revising the guess and/or target vectors, or, (C)lear all vectors and targets and examine the outputs to see if you can find clues as to the difficulties. Often, the desired targets may not be reachable, given the constraints you have specified. In all cases, if you have spent some effort reaching this point, (w)rite the model to save you work because a floating point error that could cause a crash may occur soon.

Iteration is complete but some results may not be near their targets.

If the text associated with this message is ``info=1", and a listing of the all current guesses is followed by all current target - result values, this is a WARNING message, and not strictly an error. It may occur quite frequently. This message is produced by a secondary convergence check that is necessitated by the solver's inclination to be `satisfied' with agreement that may not meet the users standards. The check is inadequate; it simply asks if the mean square error of targets - results is at least 100 times less than tolerance (see Sec IV.H). Based on the relative magnitude of the target values, this threshold may be inappropriate. When this error message occurs during a plot sweep, the line written to the .plt file will be preceded by an `*' to indicate that it requires closer examination. The most common cause of this message is inadequate agreement between results and targets at a HARDEnd or SOFTEnd. Often, the message will occur for values that are only slightly off. For a model that has this problem, a good way to judge the quality of the results is to add the residual work or enthalpy flow (parameter E or F to the plot list. If the residual flow is orders of magnitudes less than the maximum work flow, the accuracy can usually be accepted. You may also consider setting the normalization mode to 2 (see Sec IV.H) to increase the significance of the endpoint errors.

Input

The following messages can occur when DELTAE is reading in a model description file:

i numerical parameters expected and only j were found in segtype segment, Segment number n. Edit model file and restart. Last input was:

This message indicates that an input parameter could not be converted into a floating point value. The value may contain stray, inappropriate characters, or one or more lines may be missing and DELTAE may be trying to read the fluid name as the numerical parameter it needs. For a freetarget, be sure you have specified the initial Target value first, even if you do not intend to use it.

Unknown segment type: segtype.

The string at the beginning of the segment description does not match any segments in the library. Be sure that at least the first five characters are UPPERcase. The error could also by stray lines; for example, specifying the plate type twice.

Illegal fluid: fluid string.

This message occurs when DELTAE cannot find the requested fluid in the internal library or as a fluid.tpf file in the current directory. Check the spelling of the fluid and be sure that there are enough spaces to fill a 10-character field before any other text occurs. If you are using an external fluid, be sure the file is present in the same directory. If all this appears correct, you may have one line too many of numerical parameters (the giveaway here will be the contents of fluid string).

Unknown plate material: plate string.

The comments regarding the Illegal fluid message, above, also apply to the plate (solid) specification; however, the default ideal solid type may also be specified by a blank line. If this is the intent, be sure that a blank line truly separates each segment module.

Error reading segment/parameter address in segtype segment, Segment number n.

This error occurs while reading in one of the freetargets (see Sec. V.B.7) or when processing a sameas reference. The characters read do not decode to a valid address in the model.

More than 5 external fluids found....

More than 5 external solids found....

Only five distinct types of user-defined fluids or plates are allowed in a model at one time.

Guess/Result vectors are too long. Reduce count before proceeding.

The maximum problem order for this version of DELTAE is 10.

Too many plot parameters are selected. Reduce count before proceeding.

Up to 13 parameters for plotting can be specified, and the first N of these, where N is the guess vector length, will be selected automatically; these cannot be cleared. You must clear one of the user-selected parameters. In addition, one or two independent variables are also part of the `plot' file.

Nested TEE files are not permitted...compile one at a time.

An input file named in a TEE statement in turn contains another TEE statement. This is not supported. Running DELTAE on the input file first will generate a combined file that can then be included as a branch.

Model editing

The messages below occur when a model is being modified online:

*** sameas relationship cancelled...

The parameter you are affecting, by using it in the guess vector, making it an independent plot variable, or (m)odifying it, is not specified directly, but through a sameas statement. This connection is severed, and the parameter takes on the value it currently has, until you (or DELTAE) give it another.

*** Special mode affecting this value must be disabled first.

This parameter is linked back to another parameter that may change, and thereby, modify this value. Such a link is not appropriate if you are trying to set the value independently, or if DELTAE will try to do so while it is plotting or iterating; therefore, you will get the message above when you are try to modify it or make it a guess or an independent plot variable. (d)isplay this segment to find the root of this link that must be cleared. It is indicated in () to the right of the parameter description.

This variable must be cleared from the guess vector first.

A guess vector member cannot be the target of a link (it may be the root), or an independent plot variable, nor may it be specified with a sameas statement.

This parameter is part of a plot loop. It cannot participate in the guess vector.

Using this parameter as a guess would alter the independent variable of the plot loop as the solver iterates.

This output is not in any vector.

An attempt was made to (c)lear a parameter that has not been (u)sed or (p)lotted in the target or plot vectors.

WARNING: could not find appropriate default targets. Modify iteration vectors before solving this model.

While trying to generate an set of guess and target vectors, DELTAE could not find anything suitable. Be sure all HXFRST, STK*s, and HXLASts (or HXMIDls) are matched properly, and if this is not the problem, DELTAE is not smart enough to help in this case: set your vectors manually.

Consistency checks

These errors are detected when DELTAE begins processing during a (r)un:

FATAL Error: First segment must be BEGIN.

A BEGIN segment is required as the first segment for any model you intend to (r)un; without it, DELTAE has no values for the initial conditions.

SAMEAS parameter types do not match SAMEAS error: Seg# n, Parameter p.

Except for freetargets (see Sec. V.B.7), all parameters specified by sameas must have a parameter description that matches the root values description through the first four characters. Hence, parameter a in a duct may come from areaI or areaF of a cone, but not from its length.

Circular reference found processing SAMEAS Circular SAMEAS: Seg# n.

This parameter is not rooted in an actual value. It is specified by a sameas that, either directly or through additional references, refers back to the same address.

WARNING: you have i guess vector members and j target vector members defined. You must either add k new target parameters or delete k guesses.

The guess and target vectors have different lengths. You must take some action to balance them.

Adjustable length segment cannot refer to itself.

The length of this segment (parameter c) is either linked to itself or to another segment's length that, either directly or through additional segments, is linked back to this segment.