The procedure statements follow the conventions of FORTRAN 77 along with the addition of the special Calculator Intrinsic Functions . Each statement contains a maximum of 80 characters. An ampersand (&) at the end of a line indicates continuation on the following line. All lines of code except the PROCEDURE statement may be preceded by a unique numeric label from 1 to 99999 (denoted by "nn" in the statement syntax).
A currency sign ("$" in United States) causes all following data on the remainder of the line to be interpreted as a comment rather than a code (Not "C" as in FORTRAN).
The statement RETURN signals the end of the procedure section. If there are two RETURN statements, only the lines prior to the first RETURN are compiled.
Note that you must not use statements such as "SUBROUTINE", "MODULE", or "FUNCTION" to begin the procedure section.
All the data types in the FORTRAN-based statements in the procedure section of the calculator module must be calculator supplied arrays or numeric constants. Some of the arrays can be used only on the right hand side of the statements, while the others can be used on both sides. The C( ) (Constants ), P( ) (Parameters ) and the labels for Results have to be initialized in the View area by pushing the appropriate buttons. The following table lists all the supplied arrays and the form in which they can be used of in the procedure statements:
|
Array name and form |
Default Range |
Description and Comments |
|
Cn or C(index) |
1<= n<= 50 |
|
Pn or P(index) index = expression |
1<=n<= 50 |
|
Vn or V(index) index = expression |
1<=n<=200 |
A floating-point work array used on either the left of right hand side of assignment statements. They are initialized to a large negative value and are not available outside the calculator. |
|
Rn or R(index) n = Result number index = expression |
1<=n<=200 |
The array of calculator results, used on either side of assignment statements. This results vector is available to other flowsheet modules external to the calculator module. These elements are initialized to a large negative values and can be assigned a descriptive label using the Results Table. |
|
IXn or IX(index) n = IX array index |
0<=n<=9 |
An array of integer values. It may be used on either side of assignment statements. The form IX(index) is invalid in a DO Statement, since FORTRAN does not permit subscripted variables as DO loop indices. |
|
ISn |
0<=n<=9 |
An array of elements used as indices of DO loops for stepping through a series of streams in the order defined in the Stream Sequence Table. It may also serve as the stream index in Calculator Intrinsic Functions. |
You can use the variable ISOLVE to control the flowsheet calculations, based on the calculator results. It is initialized to zero upon each entry into the calculation procedure and you will have to assign all subsequent values using an Assignment Statement. The following table lists all the allowed values for the flags:
|
Flag Setting |
Description |
|
0 |
The calculator has not yet executed (default) or has solved successfully. |
|
1 |
The calculator has solved. |
|
2 |
The calculator did not solve but continue flowsheet calculations within a recycle loop. |
|
3 |
The calculator did not solve. All calculations stop unconditionally. |
|
4 |
The calculator solved but stop all subsequent flowsheet calculations. This sets the flowsheet solution flag to "SOLVED" |
The following table list the mathematical operations allowed in expressions of the procedure statements:
|
Symbol |
Description |
|
+ |
Addition |
|
- |
Subtraction |
|
* |
Multiplication |
|
/ |
Division |
|
** |
Exponentiation (raise to a power) |
User-defined Variables and Arrays
Standard FORTRAN variables may be used in CALCULATORS instead of, or in addition to, the supplied V and IX arrays. They may be up to 8 characters long and may not duplicate the names of any supplied variables; otherwise they follow the conventional FORTRAN rules.
DIMENSION variable (subscripts), variable (subscripts), ...
The DIMENSION statement is used to define one or two-dimensional arrays. Each subscript may be an integer constant, or two integer constants separated by a colon to specify both the lower and upper array bounds.
REAL variable {(subscript)}, variable {(subscript)}, ...
INTEGER variable {(subscript)}, variable {(subscript)}, ...
These statements are used to explicitly specify the type of a variable.
Examples:
DIMENSION A(20,20), B(20), X(20)
REAL MASS
INTEGER COUNT, TAB(100)
REAL REVENU(1990:1995), PROFIT(1990:1995), LOSS(1990:1995)
Note: A variable may only appear once on these statements. The following is valid in standard FORTRAN, but not in the CALCULATOR:
REAL MOLWT
DIMENSION MOLWT(50)
Both standard FORTRAN and the CALCULATOR accept this equivalent form:
REAL MOLWT(50)
Syntax
nn V(i) = expression
nn R(i) = expression
nn IX(i) = expression
nn ISOLVE = expression
Operator Precedence
The operations on a given statement are executed in the following order:
Expressions within parenthesis ( ) (evaluated innermost first)
Functions (evaluated second)
Exponential (**) (evaluated third)
Multiplications and divisions (*, /) (evaluated fourth)
Additions and subtractions (+, -) (evaluated fifth, left to right)
For calculations with the same precedence, expressions are evaluated from right to left for exponentials and left to right for all others.
Calculation Flow Control Statements
The flow of control within the calculator procedure can be controlled using the following FORTRAN statements:
Syntax: nn GOTO mm
Branches to statement with label mm unconditionally. GO TO written as two words is also supported.
Syntax: nn CONTINUE
This statement serves as a branch destination or the end of a DO loop. It performs no calculations.
Syntax: nn IF (expression) conditional clause
This statement allows logical branching during calculations. If the parenthetic expression is true, it executes the conditional clause, which may be any procedure section statement except RETURN, IF or DO. The following table lists all the logical operators allowed in the expression:
|
Operator |
Description |
|
.EQ. |
equal to |
|
.NE. |
not equal to |
|
.LT. |
less than |
|
.GT. |
greater than |
|
.GE. |
greater than or equal to |
|
.LE. |
less than or equal to |
|
.AND. |
both true |
|
.OR. |
either true |
|
.EQV. |
equivalent |
|
.NEQV. |
not equivalent |
|
.NOT. |
true/false toggle |
Syntax: nn IF (expression) THEN
ELSEIF (expression) THEN
ELSE
ENDIF
The standard FORTRAN block IF statements are supported. ELSE IF and END IF (written as two words) also are accepted. Block IF constructs may be nested.
Syntax: nn DO mm IXn = i,j,k (or)
nn DO mm ISn = sid1, sid2
This statement indicates the beginning of DO loops having a range extending through statement label mm. Specially designated indices must be used for DO loop counters. IXn (a Calculator Supplied Array) requires integer values for the initial and final indices "i" and "j". The incremental step index "k" is optional and defaults to 1.
It is also possible to loop on streams, with stream label sequence as defined by the order in the Stream Sequence Table . ISn requires stream sequence's initial and final indices sid1 and sid2. All the streams defined within this range are iterated through and therefore no incremental step index is allowed.
All the FORTRAN intrinsic functions can be used in the calculator procedure statements. The following table lists all the available functions (all function parameters must be real numbers):
|
Function |
Description |
Result Type |
|
ABS(x) |
Absolute Value |
real |
|
DIM(x) |
Positive Difference |
real |
|
EXP(x) |
Exponential e |
real |
|
INT(x) |
Truncation |
integer |
|
LOG(x) |
Natural Logarithm |
real |
|
LOG10(x) |
Common Logarithm |
real |
|
MIN(x,y,...) |
Minimum Value |
real |
|
MAX(x,y,...) |
Maximum Value |
real |
|
MOD(x,y) |
Remainder |
real |
|
NINT(x) |
Nearest Integer |
integer |
|
SQRT(x) |
Square Root |
real |
|
SIN(x) |
Sine (radians) |
real |
|
COS(x) |
Cosine (radians) |
real |
|
TAN(x) |
Tangent (radians) |
real |
|
ASIN(x) |
Arc Sine (radians) |
radian |
|
ACOS(x) |
Arc Cosine (radians) |
radian |
|
ATAN(x) |
Arc Tangent (radians) |
real |
|
SINH(x) |
Hyperbolic Sine |
real |
|
COSH(x) |
Hyperbolic Cosine |
real |
|
TANH(x) |
Hyperbolic Tangent |
real |
Calculator Intrinsic Functions
The Calculator module contains special intrinsic functions which allow you to retrieve component and stream properties directly. For these functions, the component identifying number and stream label are used as parameters. The streams identifier must have been selected in for the calculator Stream Sequence Table . Property values are retrieved in the dimensional units used for the simulation input. The total number of components and streams may also be retrieved and used as limits for loop calculations, etc.
The following table lists the available Calculator Intrinsic Functions:
cno : Integer component number which is either an actual integer or an IXn value.
sid : Stream identifier of ISn value.
|
Function |
Description of Property |
|
CMW(cno) |
Molecular Weight |
|
CNBP(cno) |
Normal boiling temperature |
|
CSPGR(cno) |
Specific gravity (60F/60F) |
|
CTC(cno) |
|
|
CPC(cno) |
Critical pressure |
|
CVC(cno) |
Critical volume, cc/gm-mole |
|
COMEGA(cno) |
Acentric factor |
|
Stream Component |
Properties |
|
SCMF(cno, sid) |
Molar fraction of component in stream |
|
SCWF(cno, sid) |
Weight fraction of component in stream |
|
SCVF(cno, sid) |
Standard liquid volume fraction |
|
SCMR(cno, sid) |
Molar rate of component in stream |
|
SCWR(cno, sid) |
Weight rate of component in stream |
|
SCLVR(cno, sid) |
Standard liquid volume rate of component |
|
SCGVR(cno, sid) |
Standard gas volume rate of component |
Stream |
Properties |
|
SMR(sid) |
Mole rate of stream |
|
SWR(sid) |
Weight rate of stream |
|
SLVR(sid) |
Standard liquid volume rate of stream |
|
SGVR(sid) |
Standard gas volume rate of stream |
|
STEMP(sid) |
Stream temperature |
|
SPRES(sid) |
Stream pressure |
Miscellaneous |
Properties |
MAXC |
|
|
MAXS |
Maximum number of streams in the simulation |
Stream Property Storage Subroutines
PRO/II contains special subroutines which store a calculator supplied array element as a stream property or a stream component property. The values being stored must be computed in the dimensional units used for data input. The resulting stream is flashed at the new conditions to determine its thermodynamic state.
Syntax: nn CALL SRXSTR(type, value, sid)
This subroutine is used to store an overall stream property. The parameters for this subroutine are:
type: The stream property to store. The following table lists the available options:
|
type |
Description |
SMR |
mole rate of stream |
|
SWR |
weight rate of stream |
|
SLVR |
standard liquid volume rate |
|
SGVR |
standard gas volume rate of stream |
|
STEMP |
stream temperature |
|
SPRES |
stream pressure |
value: The value of the property to be stored in the stream. It can be a numeric value or a descriptor identifying a variable.
sid: The stream identifier in which the property has to be stored. The identifier can be one of the streams listed in the Stream Sequence Table , or it can be an element of array IS in the form ISn.
Example: CALL SRXSTR( SPRES, R(2), STRM004 )
The value element 2 from array R is stored as the pressure of stream STRM004.
Syntax: nn CALL SRVSTR (type, array, sid, i, j)
Use this call to store a range of values representing component stream properties from a calculator array into a stream. The parameters for the subroutine are:
type: The component property to be stored in the stream. The following table lists all the available options:
|
Type |
Description |
SCMR |
molar rate of component in stream |
|
SCWR |
weight rate of component in stream |
|
SCLVR |
component standard of liquid volume rate |
|
SCGVR |
component standard gas volume rate |
array: Initial element of a calculator supplied array containing values to store as properties of components in a stream.
sid: Identifier of the stream in which the property has to be stored. It may be any stream identifier selected in the calculator Stream Sequence Table , or an element of IS in the form ISn
i, j: Component id numbers. They indicate the first and last components of the stream, respectively, for which property is stored.
Example: CALL SRVSTR( SCMR, V(3), STRM1, 2, 5 )
The values of elements V(3) - V(6) are stored as the molar flow rates of components 2 - 5 in stream STRM1.
Syntax: nn DISPLAY { R(i:j), P(i:j), C(i:j), V(i:j), IX(i:j), IS(i:j) }
This statement prints out array values during calculations. The position of DISPLAY statements in the procedure section determines when values are printed. Entries "i" and "j" refer to the first and last elements of the array to print. If they are absent, the entire array is printed.
Syntax: nn FORMAT ( item, item, … )
The following items are allowed:
Standard FORTRAN rules are used when:
The variable list in the WRITE statement is exhausted but there are still more FORMAT items.
The list of FORMAT items is exhausted but there are still variables in the WRITE statement.
Syntax: nn OPEN ( FILE = FileID, ACCESS=OVERWRITE or APPEND )
This statement opens a file for calculator output (using an OUTPUT statement). It automatically closes any previously opened file. If neither access option is given, the default is OVERWRITE. Note that the OUTPUT statement performs the actual write to files.
The default output file is named current_FileID.CAL. The "current_FileID" is the name of the simulation file that is being run. A unique file name may be specified, if necessary; however, it still will have the .CAL extension.
Syntax: nn OUTPUT { R(i:j), P(i:j), C(i:j), V(i:j), IX(i:j), IS(i:j) }
This statement prints out the array values to the currently open file (that has been opened using an OPEN statement). Multiple OUTPUT statements may be used. They may appear at any time following an OPEN statement.
Entries "i" and "j" refer to the first and the last elements of the array to print. If they are absent, the entire array is printed.
Syntax: nn TRACE option
This statement controls printing of an historical trace as calculations proceed. This facilitates debugging the code in the calculator procedure. The options available are:
ON Print the line number, statement number and (a) action taken, or (b) new variable value, as each statement executes.
BRANCH Print TRACE information only for branching statements such as IF, GOTO or DO.
OFF Turn off all TRACE options.
Syntax: WRITE (*, fmt) var, var, var, … )
In standard FORTRAN, the first entry within the parentheses may be either a unit number or an asterisk to indicate that the standard output file is to be used. However, only the asterisk is allowed within the Calculator.
There are three ways to output arrays and array elements in standard FORTRAN:
Calculation Termination Statements
Syntax: nn STOP
This statement stops all flowsheet calculations and proceeds directly to the output report. The Solution Flag for the entire flowsheet is set according to the user defined value of ISOLVE.
Syntax: nn RETURN
This statement signals the end of the calculator procedure of the calculator and must appear as the last statement in the procedure section. Only one RETURN statement is allowed in the PROCEDURE, and it is required. The Solution Flag for the calculator is set according to the user-defined value of ISOLVE.