问题
I have an old fortran code that I am attempting to decipher and understand what is going on so I can modify it. Unfortunately I am a bit of a neophyte in fortran so I am having trouble figuring out this statement.
C 15/04/97 IBM VERSION ECIS96 CALC-000
SUBROUTINE CALC(W,NW,DW,IDMX) CALC-001
C MAIN SUBROUTINE OF THE PROGRAMME CALC-002
C W,NW,DW ARE THE WORKING SPACE IN EQUIVALENCE BY CALL,STARTING AS CALC-003
C REAL*8. THEY ARE RESPECTIVELY REAL, INTEGER AND DOUBLE PRECISION. CALC-004
C IDMX IS THE LENGTH OF DW. CALC-005
C CALC-006
C ADDRESSES IN THE WORKING FIELD DEFINED HERE (FOR OTHERS, SEE CALX) CALC-007
C IN COMMON /DECOU/ CALC-008
C 34- NT HERE, ALSO REDUCED NUCLEAR MATRIX ELEMENTS CALC-009
C 35- NIVQ TABLE OF MULTIPOLES CALC-010
C 36- NIVY TABLE OF FORM FACTOR IDENTIFICATION IVY (FOR COMPUTATION)CALC-011
C 37- NIVZ TABLE OF FORM FACTOR IDENTIFICATION IVZ (FOR USE) CALC-012
C 38- NCOI ADDRESS OF THE TABLE FOR DISCRETISATION OF CONTINUUM CALC-013
C 39- MIPI SAME AS NIPI FOR THE DISCRETISATION OF CONTINUUM CALC-014
C 40- NXD ADDRESS OF WEIGHTS AND STEPS OF CONTINUUM CALC-015
C 41- MWV SAME AS NWV FOR THE DISCRETISATION OF CONTINUUM CALC-016
C 42- NIXT TRANSMISSION COEFFICIENTS OF UNCOUPLED STATES CALC-017
C 43- NTY TEMPORARY RESULTS OF COMPOUND NUCLEUS FOR INTERPOLATION CALC-018
C 44- NTX PARTIAL REACTION CROSS SECTIONS AND COMPOUND NUCLEUS CALC-019
C 45- NRY COMPOUND NUCLEUS COEFFICIENTS CALC-020
C 46- NRCO STRENGTH OF COULOMB CENTRAL POTENTIALS FOR CORRECTIONS CALC-021
C 47- NRDO STRENGTH OF COULOMB TRANSITION POTENTIALS FOR CORRECTIONSCALC-022
C 48- NVC1 REAL POTENTIALS CALC-023
C 49- NVC2 IMAGINARY POTENTIALS CALC-024
C 50- NNC FIRST FREE ADDRESS AFTER COMPUTATION OF POTENTIALS CALC-025
C 51- NCX FIRST FREE ADDRESS FOR COMPUTATION OF POTENTIALS CALC-026
C OTHER INTEGER DATA OF COMMON /DECOU/ CALC-027
C 52- IDMT TOTAL WORKING FIELD LENGTH AS SINGLE PRECISION CALC-028
C 53-98 SEE CALX CALC-029
C 99- KXT NUMBER OF PENETRABILITIES FOR UNCOUPLED STATES CALC-030
C100- NRZ NUMBER OF RESULTS TO SAVE FOR MINIMUM CHI2 CALC-031
C101- NTZ NUMBER OF MEMRIES TO INITIALISE TO ZERO FOR SCATTERING CALC-032
C MATRIX AND COMPOUND NUCLEUS RESULTS CALC-033
C102- LMAX3 EFFECTIVE NUMBER OF COULOMB FUNCTIONS CALC-034
C103- IPM NUMBER PF J VALUES USED FOR SCATTERING MATRIX (IN CAL1) CALC-035
C104- IPK NUMBER PF J VALUES USED FOR COMPOUND NUCLEUS (IN CAL1) CALC-036
C105-110 SEE CALX CALC-037
C CALC-038
C IN COMMON /DBLPR/ CHI2,CHI2M: CHI-SQUARE AND MINIMUM CHI-SQUARE CALC-039
C CM,CHB: NUCLEAR MASS AND H BAR CALC-040
C CK,CMB,CCZ: DERIVED CONSTANTS CALC-041
C XE,XM,XN: RELATIVISTIC ENERGY AND MASS (COLF) CALC-042
C XZ: CONVERSION FACTOR TO MILLIBARNS CALC-043
C FOR COMMONS /POTE1/ AND /POTE2/ SEE REDM CALC-044
C FOR COMMON /NCOMP/ SEE CALX, LECT AND COLF CALC-045
C CALC-046
C*some information on logical variables that is unimportant to this*
DOUBLE PRECISION CHI2,CHI2M,CM,CK,CHB,CMB,CZ,CCZ,XE,XM,XN,XZ,DW(1)CALC-095
LOGICAL LO(250) CALC-096
DIMENSION W(1),NW(1) CALC-097
COMMON /DECOU/ NJIT,NIPP,NIPI,NWV,NIPH,NSCN,NPAR,NNIV,NFIS,NGAM,NPCALC-098
1OT,NBETA,NFM,NTGX,NDONN,NRC,NIW,NDE,NISE,NNVI,NNWI,NCC,MCC,NXA,NAMCALC-099
21,NFAC,NFAM,NPAD,NFG,NXG,NSM,NRES,NXX,NT,NIVQ,NIVY,NIVZ,NCOI,MIPI,CALC-100
3NXD,MWV,NIXT,NTY,NTX,NRY,NRCO,NRDO,NVC1,NVC2,NNC,NCX,IDMT,NCOLL,NJCALC-101
4MAX,ITERM,NPP,JDM,JIT,NSEC,LMD,MCM(2),NCOLS,NCOLT,KMAX,KMIN,NVA,NBCALC-102
5ET,NBT1,LMX,LMAX1,NLT,ISM,IQM,IQMAX,MS1,MS2,NCT(6),KBA,KAB,KBC,KCCCALC-103
6,NJC,JTX,JTH,NCOLR,NREC,NTOT,NFA,LMAX2,KE,ITEMM,NPLACE,KXT,NRZ,NTZCALC-104
7,LMAX3,IPM,IPK,H,BJM,EITER,ACONV,CONJ,ASPIN CALC-105
COMMON /DBLPR/ CHI2,CHI2M,CM,CK,CHB,CMB,CCZ,XE,XM,XN,XZ CALC-106
COMMON /POTE1/ ITX(16),IMAX,INTC,INLS,INVC,INVD,ITXM CALC-107
COMMON /POTE2/ ITY(8),INVT,INTV,INSL,NPX CALC-108
COMMON /NCOMP/ NSP(3),NFISS,NRD,NCONT,NCOJ,ACN1,ACN2,NCONS,NIE,NCOCALC-109
1LX,NDP,NDQ,AZ(6),BZ1,BZ2,BZ3,TG0,BN,FNUG,EGD,GGD,TG1,SGSQ CALC-110
If it helps this is how the function is called.
C 18/12/87 IBM VERSION CONVEX ECIS88 ECIS-000
REAL*8 W(600000) ECIS-001
COMMON W ECIS-002
CALL CALC(W,W,W,600000) ECIS-003
STOP ECIS-004
END ECIS-005
I already understand the line continuations and that for lines CALC-099 through CALC-105 the first non-whitespace numbers are just counting the continuations since the compiler is jumping to column 7 for the continuation.
What I do not understand is how the types are decided. Is it something automatically determined on first assignment, my understanding of how common blocks work makes this seem unlikely. Is it something in the naming, is the first character somehow determining it?
Also, what are the dimension statements doing here? If the array is 600,000 long why is the dimension statement "setting" its length to 1, or is it doing something I am not seeing?
回答1:
Both parts of your question are something that horrifies modern people.
First, implicit typing. Variables, unless they have an explicit type, take an implicit type. Variables beginning I-Nare INTEGER and others are REAL. The IMPLICIT statement overrides this, however, so look out for that (never underestimate what evils programmers can do). Also, note that IMPLICIT NONE is a later addition to the standard.
Second, in subroutines DIMENSION(1) (or equivalent) was an alternative to DIMENSION(*).
回答2:
The default typing in FORTRAN77 is
IMPLICIT REAL(A-H, O-Z), INTEGER(I-N)
Which means variables that start with letters i,j,..,n are INTEGER and the rest are REAL.
Reference URL
来源：https://stackoverflow.com/questions/21174355/how-are-the-types-in-this-common-statement-specified