topic Re: A comment from 1991 in Fortran in Intel® Fortran Compiler

A comment from 1991 in Fortran

JohnNichols — Sat, 25 Jan 2025 16:42:11 GMT

I needed a program to draw bridge profiles so I grabbed a program from 1991 to draw rising mains from a text file.

! ! NATURAL SURFACE ! ! ! LAST PLOT POINTS FIX FOR WMS/SWP ! ! >>>>>>>>>>>>>>>>>>>>>>>>THIS COULD BE FLAWED<<<<<<<<<<<<<<<<<<<<< IH1=I-1 DO 600 J11=1,7 NH1=NCHAIN(IH1) IF (NH1 .EQ. 22) THEN IH1=IH1-1 ELSEIF( NH1 .EQ. 28) THEN IH1=IH1-1 ELSEIF(NH1 .EQ. 38) THEN IH1=IH1-1 ELSEIF(NH1 .EQ. 77) THEN IH1=IH1-1 ELSEIF(NH1 .EQ. 78) THEN IH1=IH1-1 ENDIF 600 CONTINUE

I had to laugh, when I wrote this code with this comment in 1991.

IF(NYNEXT .NE. 22 .AND. NYNEXT .NE. 28 .AND. NYNEXT .NE. 38 .AND. NYNEXT .NE. 77 .AND. NYNEXT .NE. 78 .OR. NY .EQ. 31) THEN

Jim: Is there a better way to do the if statement? This is from 1991.

Me to student : What are you studying?

Student : FEM

Me What language?

Student: Python

Me: Ah.. you want a fast language

Student: It is better then MATLAB.

Me: Ah.....................

Re: A comment from 1991 in Fortran

andrew_4619 — Sun, 26 Jan 2025 01:30:46 GMT

If (any(nh1==[22,28,38,77,78])) ih= ih1-1

Re: A comment from 1991 in Fortran

JohnNichols — Sun, 26 Jan 2025 20:28:53 GMT

Any is not in my MS Fortran 5.1 manual written in 1991.

Pity I like that manual.

Thanks - learnt something new. I will not comment about it potentially being syntactic sugar, although it is simpler.

Re: A comment from 1991 in Fortran

andrew_4619 — Mon, 27 Jan 2025 03:54:47 GMT

Well you could have constructed an integer array and made a do loop with an if statement in it. That would be much shorter code also. I remember using that old ms Fortran and had no opinion good or bad at the time. If I had to use it now I would consider it a restrictive buggy bag of ****.

Re: A comment from 1991 in Fortran

JohnNichols — Tue, 28 Jan 2025 22:48:47 GMT

Thanks. Old MS Fortran manuals are good as they provide simple examples and clear explanations for a lot of Fortran stuff.

Old Fortran cannot do what a modern compiler can do I accept that, but the manuals were better then, as you could read them in bed. Now they are html and example poor.

Re: A comment from 1991 in Fortran

JFH — Thu, 30 Jan 2025 06:48:36 GMT

I agree about old manuals. When I was using Algol many of us used one vendor's inexpensive readable manual even though our one compiler was a different vendor's. There are books e.g. Modern Fortran Explained by Metcalf et al. that could be read in bed

Re: A comment from 1991 in Fortran

GVautier — Thu, 30 Jan 2025 14:42:41 GMT

Fortunately, it was not arithmetic if. Imagine

if (nhi-22) 10,90,10 10 if (nhi-28) 11,90,11 11 ... goto 99 90 ih1=ih1-1 99 continue

Re: A comment from 1991 in Fortran

jimdempseyatthecove — Thu, 30 Jan 2025 16:00:18 GMT

In your first source:

IH1=I-1 DO J11=1,7 NH1=NCHAIN(IH1) SELECT CASE(NH1) CASE(22,28,38,77,78) IH1=IH1-1 DEFAULT EXIT ! Note, if none of the above, exit loop as NH1 is unchanging END SELECT END DO

Jim

Edit

@andrew_4619 's solution is much better

Re: A comment from 1991 in Fortran

JohnNichols — Thu, 30 Jan 2025 19:58:36 GMT

I do, but you cannot read the Intel Fortran 2025 manual in bed unless you take a computer.

Re: A comment from 1991 in Fortran

JohnNichols — Thu, 30 Jan 2025 19:59:55 GMT

IN order to do some of the plastic analysis I am using programs from late 1960's and early 1970's and they use arithmetic if, slowly fixing them, but if it is not broken why fix it.

Re: A comment from 1991 in Fortran

JohnNichols — Thu, 30 Jan 2025 20:01:19 GMT

Should have thought of case been using it a lot.

I like Andrew's solution, but which one takes up the least assembler code and which one is fastest.

Re: A comment from 1991 in Fortran

andrew_4619 — Thu, 30 Jan 2025 20:29:40 GMT

The speed difference of any of them is probably irrelevant, easiest to read, understand and maintain would get my vote.

Re: A comment from 1991 in Fortran

GVautier — Fri, 31 Jan 2025 08:24:56 GMT

A piece of code slightly modernized but in which I never succeeded to replace the arithmetic if. The code do what it is supposed to do but I never understood neither how neither why.

intli=0 9 if (lign-ptal_g)999,15,10 10 if (lign-ptal_d)11,20,999 11 if (xa-xb)20,999,15 15 isens=1 lim=ptal_d goto 30 20 isens=-1 lim=ptal_g 30 do l=lign+isens,lim,isens do n=npro,npro,-1 call inseg_old(xa,ya,xb,yb,p(n ).x(l),p(n ).y(l) s ,p(n-1).x(l),p(n-1).y(l) s ,x,y) if ((x-xa)*(x-xb))34,34,40 34 if ((x-p(n).x(l))*(x-p(n-1).x(l)))35,35,40 35 if (p(n).v(l))36,36,100 36 if (p(n-1).v(l))40,40,100 40 if (p(n-1).y(l)-ymin)41,45,45 41 if (p(n-1).y(l)-p(n).y(l))50,50,45 45 continue enddo 50 continue enddo return 100 intli=1 xint=x yint=y 999 return

Re: A comment from 1991 in Fortran

jimdempseyatthecove — Fri, 31 Jan 2025 14:58:47 GMT

Presumably @andrew_4619 's solution is inside the DO 600 loop and thus will execute 7 times regardless of the length of the chain.

As to if which method is faster, will depend on the length of the chain.

Jim Dempsey

Re: A comment from 1991 in Fortran

JohnNichols — Fri, 31 Jan 2025 15:06:07 GMT

= If (any(nh1==[22,28,38,77,78])) ih= ih1-1

If you like Lisp and I love Lisp then this would be your first choice.

If you are rapidly developing Fortran code this is easy to understand although Verbose, its only problem is say 100 items, but

it is easy to forget( in Version 1 top of page) in counting or adding numbers correctly, try MySQL commands with more than 4 parameters.

IH1=I-1 DO J11=1,7 NH1=NCHAIN(IH1) SELECT CASE(NH1) CASE(22,28,38,77,78) IH1=IH1-1 DEFAULT EXIT ! Note, if none of the above, exit loop as NH1 is unchanging END SELECT END DO

This is Zen like, obviously the person who wrote this read Zen and the Art of Motorcycle maintenance in their misspent youth.

As an early Fortran programmer I read the book and summarized it for an English student who had more homework than I did.

For Zen read C.

Al of them meet Andrew's criteria for different reasons. It is the old argument, how does one do hill climbing, slow and steady or fast and parched.

Although technically 1 is syntactic sugar on old English Fortran, beloved of no-one.

of course @mecej4 would tell me to knock of the games and just concentrate on the Fortran. Although yesterday I was asked by a student, who is the Mother of Zeus, she was doing a crossword, I said Raia but it is Rhea.

Re: A comment from 1991 in Fortran

jimdempseyatthecove — Fri, 31 Jan 2025 15:22:01 GMT

Some of the older coder's style may have written the loop as follows:

IH1=I-1 DO 600 J11=1,7 NH1=NCHAIN(IH1) IF(NH1 .EQ. 22) IH1=IH1-1 IF(NH1 .EQ. 28) IH1=IH1-1 IF(NH1 .EQ. 38) IH1=IH1-1 IF(NH1 .EQ. 77) IH1=IH1-1 IF(NH1 .EQ. 78) IH1=IH1-1 600 CONTINUE

Fewer punched cards.

Jim

Re: A comment from 1991 in Fortran

andrew_4619 — Fri, 31 Jan 2025 15:41:25 GMT

Although technically 1 is syntactic sugar on old English Fortran, beloved of no-one.

I don't actually agree, there are several things happening in that one line statement all of which have many different potential usage cases.

1] constructing a list of integers in an array

2] constructing a temporary logical array comparing a scaler to an array.

3] Using the ANY function to see if any logical in the array is true and if so......

4] executing the IF construct.

The use of whole array operations is fundamental to the Fortran language from Fortran 90 onwards. Personally I find that the one liner much quicker to understand than the list of ELSEIFs which I need to read all of to see what each case does. OK they all do the same thing but you do not know that without checking each line. Why write and maintain 14 lines of code when one will do? Why write code that creates unnecessary scrolling up and down the page because it is verbose? And as a final point if one wanted to change the IH1 = IH1-1 in some way you would need to change it in 5 places instead of one, whoops I missed one and made a bug....

Re: A comment from 1991 in Fortran

jimdempseyatthecove — Fri, 31 Jan 2025 15:51:38 GMT

Should @JohnNichols choose the ANY method, then after the 600 CONTINUE, he will need to insert NH1=NCHAIN(IH1) should the value of NH1 be required later in the code.

Jim Dempsey

Re: A comment from 1991 in Fortran

JohnNichols — Fri, 31 Jan 2025 23:05:09 GMT

(map ’string #’(lambda (x y) (char "01234567890ABCDEF" (mod (+ x y) 16))) ’(1 2 3 4) ’(10 9 8 7)) → "AAAA" (setq seq ’("lower" "UPPER" "" "123")) → ("lower" "UPPER" "" "123") (map nil #’nstring-upcase seq) → NIL seq → ("LOWER" "UPPER" "" "123") (map ’list #’- ’(1 2 3 4)) → (-1 -2 -3 -4) (map ’string #’(lambda (x) (if (oddp x) #\1 #\0)) ’(1 2 3 4)) → "1010" (map ’(vector \* 4) #’cons "abc" "de") should signal an error

This is the problem with Fortran's development over the last 50 years. The developers borrow from other languages, such as ANY being similar to map from Lisp. Why not use a word that other program use and not reinvent the wheel.

I have no problem with ANY per se, just make the language closer to common things in other languages.

Re: A comment from 1991 in Fortran

andrew_4619 — Sun, 02 Feb 2025 12:30:35 GMT

I do not know lisp but ANY does not seem analogous to MAP and there is already a MAP in a widely supported Fortran extension. ANY is just an .OR. applied to an array of type logical and returns TRUE if ANY are true. ALL is the equivalent for .AND. and returns TRUE if ALL are true. Those names seem quite LOGICAL to me. ANY/ALL/COUNT (from F2003 or 2008 from memory) allow you to work with arrays rather than scalars and can make code much less verbose and can eliminate loops. I would also think it gives a compiler more chance to vectorise/optimise.