CS Computer Programming in Fortran 90 & C

Transcription

1 CS Computer Programming in Fortran 90 & C Instructor: Dr. Henry Neeman TAs: Ashwin Seshadri, Hisham Qureshi Prerequisite: MATH 1523 (Elementary Functions) or equivalent Class Meetings: Tues/Thurs 10:30-11:45am GLCH 123 Lab sections: Fridays 10:30am, 1:30pm & 2:30pm Carson 206 Note: this class is NOT for students majoring in CS or enrolled in CS option programs.

2 Syllabus for CS Spring 2000 Computer Programming in Fortran 90 & C Class: Tuesdays & Thursdays 10:30-11:45am, George Lynn Cross Hall 123 Instructor: Dr. Henry Neeman, Sarkeys Energy Center 1252 (Boyd & Jenkins) (hneeman@ou.edu, ) Office hours: Tues & Thurs 12:15-1:15pm, Sarkeys Energy Center 1252 OR BY APPOINTMENT AT LEAST 24 HOURS IN ADVANCE Note: please contact me by unless it s an emergency; please don t call the CAPS or Computer Science offices if you can t find me in my office. Labs: Fridays 10:30-11:20am (section 011), 1:30-2:20pm (012) or 2:30-3:20pm (013) Carson Engineering Center 206 TAs: Ashwin Seshadri (sashwin@ou.edu), Carson Engineering Center B18 Office hours to be announced Hisham Qureshi (hisham aq@ou.edu), Carson Engineering Center B8 Office hours to be announced Prerequisite: MATH 1523 (Elementary Functions) or equivalent Note: this class is not for students majoring in CS or enrolled in CS option programs. Material to be covered Programming in Fortran 90 (about the first half of the semester) Programming in C (the rest of the semester) Texts Programming in Fortran 90/95, 5th ed., S. Lakshmivarahan & S.K. Dhall, 1999 Available at King Kopy (Lindsey & Jenkins) Problem Solving & Program Design in C, 3rd ed., J.R. Hamly & E.B. Koffman, 1999 Required work 7-10 Programming Projects (55%) Weekly Quizzes (10%): every Tuesday at 10:30am starting Jan 25 (usually open book) Quiz questions will be taken verbatim from the homework assigned the previous Tuesday. Midterm Exam (15%): date to be announced in class Final Exam (20%): Thursday May 4 8:00-10:00am Recommended work Readings will be assigned most weeks to supplement the lectures. Weekly homeworks will be assigned every Tuesday starting Jan 18. These will form the basis for the quizzes; they will not be collected or graded. Grading: A: 90% - 100% B: 80% - 89% C: 70% - 79% D: 60% - 69% F: less than 60% I reserve the right to curve the grades as I see fit, but the curve will not be harsher than this. Web postings All printed class materials, including lecture slides, homework assignments and programming project descriptions, will be posted on the class webpage:

3 Syllabus for CS Spring 2000 (continued) Computer Programming in Fortran 90 & C Occasionally, we may need to alert the class when an issue comes up. You should check your at least once a week. Class Policies Credit for programming projects No lateness deduction: if turned in on time (by 11:45am on the due date) 25% deducted: if late one class (by 11:45am the class after the due date) No credit: if later than 11:45am the class after the due date Helping each other I encourage you to discuss homework and programming projects with each other. However, IT IS NOT ACCEPTABLE to copy each other s work. Cheating can result in suspension or expulsion, so DON T EVEN THINK ABOUT IT! Help from us If you have questions or you re having trouble with the material, we urge you to come talk to us during office hours, or to make an appointment (at least 24 hours in advance) to meet at other times, or to send us . Working on programming projects Do not wait until the last minute to start your programming projects. Developing software takes time, and may depend on the availability and reliability of systems that you have no control over. If the computers are down the night before a due date, don t count on that buying you extra debugging time it certainly won t in the real world. Studying for exams Do not wait until the last minute to start studying for exams. The best way to ensure success is to keep up with the course material, and to ask questions. Students who actively participate in lectures and come to office hours typically learn and retain the material a lot better. Will this be on the exam? Yes. Everything covered in class, readings, labs, homeworks and programming projects is fair game unless specifically stated otherwise. Disability Any student in this course who has a disability that may prevent him or her from fully demonstrating his or her abilities should contact the instructor personally as soon as possible so that accommodations necessary can be made to ensure full participation and to facilitate your educational opportunities. Be prepared to bring documentation from the Office of Disabled Student Services. Academic Misconduct All cases of academic misconduct will be reported to the Dean of the appropriate College for adjudication.

4 Outline of Fortran 90 Topics Overview of Computing Computer Organization Languages Problem Solving Variables Data Types Basic Data Types 1D Arrays Derived Data Types Assignments Expressions Numeric Non-numeric Control Structures Branching Repetition Procedures Subroutines Functions Modularity Modules Interface Blocks Input/Output Formatting Files Note: this is roughly how this part of the semester will go.

5 What is a Computer? A computer is a programmable electronic device that can store, retrieve and process data. compact disc ZIP Hello...

6 Components of a Computer System COMPUTER SYSTEM HARDWARE Physical devices SOFTWARE Sets of instructions FIRMWARE Software that lives on a chip

7 Hardware Components HARDWARE CPU STORAGE INPUT/OUTPUT Control Unit Arithmetic/ Logic Unit Registers Cache $1600/MB Proc Speed Main Memory $2/MB 100 MB/sec Hard Disk $ /MB 8-40 MB/sec BASIC I/O Keyboard Mouse Monitor Printer MULTIMEDIA Speakers Amplifier CDROM Joystick CDROM $0.003/MB 7 MB/sec etc Scanner etc Secondary Storage Zip/Jaz/etc Disk $ /MB MB/sec Magnetic Tape $0.003/MB 1 MB/sec Floppy Disk $0.21/MB 0.03 MB/sec etc NETWORKING Modem Internet Port etc

8 Central Processing Unit Fetch Next Instruction Control Unit Increment Instruction Pointer Find Data Addresses in Memory Fetch Data from Memory Execute Instruction... Store Result in Memory Arithmetic/Logic Unit Add R03 = R03 + R63 Add R02 = R00 + R01 Multiply R02 = R00 * R01 Compare Bit Shift R00 < R01? R00 << R01 R03 = ~R01... Bit Invert R00 R01 R02 R03 R63 Registers... Registers are very expensive, because they have to be etched directly into the CPU.

9 Main Memory Address Cell or Location Contents 34,359,738,367 (32 MB) We can think of memory as one contiguous line of cells.

10 The Bus The bus is the connection from the CPU to main memory; all data travel along it. CPU Main Memory

11 Loading Data from Main Memory into the CPU I want the contents of 0x12AD36BC. Zzzzz... CPU Main Memory Bus Zzzzz... CPU putt putt putt... Load 0x12AD36BC Main Memory Bus CPU Yikes! Bonk! Load Main Memory 0x12AD36BC Bus There you go! CPU -75 Main Memory Bus I ll put it in R05. CPU Bonk! -75 Zzzzz... Main Memory Bus

12 Cache The CPU runs at, say, 500 MHz. Main Memory transfers run at, say, 100 MHz. So transferring data directly between the CPU and Main Memory is a bottleneck. Cache is a smaller memory that runs at the same speed as the CPU. CPU Cache Main Memory

13 Secondary Storage Nonvolatile: data don t disappear when power is turned off Slower and cheaper than main memory Most are portable: can be easily removed from your computer and taken to someone else s Medium Size Speed Type Can Port- Popular? Drive Media (GB) (MB/sec) write? able? ( ) ( /MB) Hard Disk Mag Yes No Very /MB DVD 17 up to 13 Optic No Yes Not yet Mag Tape 7 1 Mag Yes Yes Yes DVD-RAM 5.2* 2.7 Optic Yes Yes New! Jaz Disk Mag Yes Yes No CDROM 0.63 up to 7 Optic No Yes Very CD-RW R/1.8W Optic Yes Yes No SuperDisk 0.12 up to 0.7 Mag Yes Yes Not very Zip Disk Mag Yes Yes Kind of Floppy Mag Yes Yes Very Cassette «0.001 «1 Mag Yes Yes No Historical Paper Tape «0.001 «1 Paper Once Yes No Historical Punch Card «0.001 «1 Paper Once Yes No Historical Note: all numbers are approximate as of 10 January * DVD-RAM capacity will probably grow to about 15 GB in the next few years. Media Types Magnetic: read/write, but degrade over time and can be erased by magnets Optical: often can t write, but degrade slowly and can t be erased by magnets Paper: forget about it!

14 Software Components SOFTWARE SYSTEM SOFTWARE You buy these. APPLICATION SOFTWARE You write these.

15 Kinds of System Software SYSTEM SOFTWARE OPERATING SYSTEMS MSDOS Windows MacOS PalmOS OS/2 COMPILERS/ INTERPRETERS Fortran 90 C C++ Java Perl FUNCTION LIBRARIES LINPACK BLAS LAPACK HDF NetCDF Unix Linux BSD csh HTML NCAR Graphics AIX HP-UX IRIX... TEXT PROCESSORS SPREAD SHEETS MATH/STATS SYSTEMS DATABASES vi Lotus SAS Oracle pico MS Excel Mathematica Sybase MS Word LaTeX etc. Maple Matlab dbase MS Access

16 A Simple Fortran 90 Program scarecrow 1% cat helloworld.f90!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Program: helloworld!!!!!! Module: main!!!!!! Author: Henry Neeman !!!!!! Class: CS Spring 2000!!!!!! Lab: Sec 013 Fridays 2:30pm!!!!!! Description: Prints the sentence!!!!!! Hello, world. to standard!!!!!! output.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! PROGRAM helloworld!! Declarations!! No implicitly typed variables. IMPLICIT NONE!! Execution!! Print the sentence to stdout. PRINT *, Hello, world! END PROGRAM helloworld scarecrow 2% f90 -o helloworld helloworld.f90 scarecrow 3% helloworld Hello, world! scarecrow 4% The Same Program Without Comments PROGRAM helloworld IMPLICIT NONE PRINT *, Hello, world! END PROGRAM helloworld

17 Some Basic Elements of a Fortran Program Comment Block Program statement Tells compiler to make no assumptions about any of the program s variables Program body End statement!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Program: helloworld!!!!!! Module: main!!!!!! Author: Henry Neeman !!!!!! Class: CS Spring 2000!!!!!! Lab: Sec 013 Fridays 2:30pm!!!!!! Description: Prints the sentence!!!!!! Hello, world. to standard!!!!!! output.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! PROGRAM helloworld!! Declarations!! No implicitly typed variables. IMPLICIT NONE!! Execution!! Print the sentence to stdout. PRINT *, Hello, world! END PROGRAM helloworld

18 Languages Kinds of Languages Natural Programming Converting Between Programming Languages Compilers Interpreters Assemblers

19 Kinds of Languages Natural Languages Examples: English, Chinese, Swahili, Navajo, Quechua, Maori Typically can be described by formal rules Might not be bound by these rules in everyday use Any noun can be verbed. I might could get me one o them there computers. Can mix words and syntax from multiple languages in one sentence Hey, amigo, is it all right by you if I kibbitz your chess game while I watch your anime? Can be ambiguous When did he say she was going? State the time at which he said, She was going. According to him, at what time was she going? Programming Languages Completely described and bound by formal rules Cannot mix words and syntax from multiple languages Cannot be ambiguous Words and syntax must be EXACTLY correct

20 Programming Language Hierarchy High Level Languages Examples: Fortran, C, Java, HTML Usually are standardized, so can be used on any kind of computer Typically are designed for a particular kind of application e.g., Fortran for scientific applications, C for operating system design, HTML for webpages, SAS for statistics Assembly Language: specific to a particular CPU Set of simple commands (e.g., load a value from a location in memory; add two numbers; store a value into a location in memory) Machine Language: binary code that the CPU understands directly; binary representation of assembly language

21 Converting Between Languages Compilers, interpreters and assemblers are programs that turn programs people can read into programs computers can run. Compiler converts a high level language source code of a program into a machine language executable all at once must be completed before executing the program Examples: Fortran, C Interpreter converts a high level language source code into machine language converts and executes one statement at a time conversion and execution occur while running Examples: Perl, HTML, SAS, Mathematica Assembler converts a CPU-specific assembly code into machine language like a compiler, but low level

22 Our Old Friend helloworld.f90 scarecrow 212% script helloworld.script Script started on Sat Jan 8 12:53: scarecrow 1% cat helloworld.f90!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Program: helloworld!!!!!! Module: main!!!!!! Author: Henry Neeman !!!!!! Class: CS Spring 2000!!!!!! Lab: Sec 013 Fridays 2:30pm!!!!!! Description: Prints the sentence!!!!!! Hello, world. to standard!!!!!! output.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! PROGRAM helloworld!! Declarations!! No implicitly typed variables. IMPLICIT NONE!! Execution!! Print the sentence to stdout. PRINT *, Hello, world! END PROGRAM helloworld scarecrow 2% f90 -o helloworld helloworld.f90 scarecrow 3% helloworld Hello, world! scarecrow 4% ctrl-d Script done on Sat Jan 8 12:53: scarecrow 213%

23 Compiling f90 -o helloworld helloworld.f90 F90 Source Code: helloworld.f90 Compiler Assembly Code: helloworld.s Assembler Automatically called by compiler Object File: helloworld.o Linker/Loader Executable: helloworld

24 Compiler Details f90 -o helloworld helloworld.f90 F90 Source Code: helloworld.f90 Compiler Lexical Analysis Parsing Semantic Analysis Intermediate Code Generation Optimization Assembly Code Generation Assembly Code: helloworld.s Assembler Object File: helloworld.o Linker/Loader Executable: helloworld

25 Elements of a Compiler Compiler Lexical Analyzer: identifies program s word elements Comments (ignored) Keywords (e.g., PROGRAM, END) User-defined Identifiers (e.g., helloworld) Operators; e.g. arithmetic: + - * / ** comparisons:.eq..ne..lt..le..gt..ge. array subscripting: ( ) Parser: determines the program s grammar Semantic Analyzer: determines what the program does Intermediate Code Generator: expresses, as an assembly-like program, what the program does Optimizer: makes code more efficient Assembly Code Generator: produces the final assembly code that represents what the program does Assembler: converts assembly code to machine code Linker/Loader: creates the final, executable version of the machine code

26 Compiling a Fortran 90 Statement aplusb = a + b Lexical Analysis IDENTIFIER[aplusb] EQUAL IDENTIFER[a] PLUS IDENTIFIER[b] Parsing ASSIGN VARIABLE EXPRESSION ADD VARIABLE VARIABLE Semantic Analysis ASSIGN(VARIABLE[aplusb],ADDITION(VARIABLE[a],VARIABLE[b])) Intermediate Code Generation Load a into R00 Load b into R01 R02 = R00 + R01 Store R02 into aplusb Assembly Code Generation ld r00,a ld r01,b ad r02,r00,r01 st r02,aplusb

27 Assembly Code for helloworld.f90 on a DEC Alpha Assembly Code for helloworld.f90 on a Pentium III ldah $gp, ($27)!gpdisp!1 unop lda $gp, ($gp)!gpdisp!1 unop ldq $27, for_set_reentrancy($gp)!literal!2 lda $sp, -96($sp) stq $26, ($sp) ldq $16, $$5($gp)!literal!3 jsr $26, ($27), for_set_reentrancy!lituse_jsr!2 ldah $gp, ($26)!gpdisp!4 mov 12, $1 lda $gp, ($gp)!gpdisp!4 ldq $27, for_write_seq_lis($gp)!literal!5 ldq $3, $$7($gp)!literal!6 ldah $18, 901($31) stl $31, 8($sp) stq $1, 72($sp) lda $16, 8($sp) stq $3, 80($sp) mov -1, $17 ldq $19, $$3($gp)!literal!7 lda $18, -256($18) lda $20, 72($sp) jsr $26, ($27), for_write_seq_lis!lituse_jsr!5 ldah $gp, ($26)!gpdisp!8 ldq $26, ($sp) lda $gp, ($gp)!gpdisp!8 mov 1, $0 lda $sp, 96($sp) ret ($26) pushl %ebp movl %esp,%ebp subl $24,%esp movl $.C1_283,%eax movl %eax,(%esp) call pghpf_init movl $14,%eax movl %eax,8(%esp) movl $.C1_297,%edx movl %edx,4(%esp) movl $.C1_300,%ecx movl %ecx,(%esp) call pgf90io_src_info movl $.C1_283,%edx movl %edx,12(%esp) movl %edx,8(%esp) movl $pghpf_0_+8,%eax movl %eax,4(%esp) movl $.C1_301,%ecx movl %ecx,(%esp) call pgf90io_ldw_init movl %eax,-4(%ebp) movl $13,%eax movl %eax,16(%esp) movl $.C1_304,%ecx movl %ecx,12(%esp) movl $.C1_283,%edx movl %edx,8(%esp) movl $.C1_285,%eax movl %eax,4(%esp) movl $.C1_298,%ecx movl %ecx,(%esp) call pgf90io_ldw movl %eax,-4(%ebp) call pgf90io_ldw_end movl %eax,-4(%ebp) movl $.C1_283,%eax movl %eax,(%esp) call pgf90_exit leave ret

28 Assembly Code for helloworld.f90 on a DEC Alpha Using Fortran 90 Assembly Code for helloworld.f90 on a DEC Alpha Using Fortran 95 ldah $gp, ($27)!gpdisp!1 unop lda $gp, ($gp)!gpdisp!1 unop ldq $27, for_set_reentrancy($gp)!literal!2 lda $sp, -96($sp) stq $26, ($sp) ldq $16, $$5($gp)!literal!3 jsr $26, ($27), for_set_reentrancy!lituse_jsr!2 ldah $gp, ($26)!gpdisp!4 mov 12, $1 ================>>> lda $gp, ($gp)!gpdisp!4 ldq $27, for_write_seq_lis($gp)!literal!5 =============================>>> ldq $3, $$7($gp)!literal!6 ldah $18, 901($31) ==========>>> stl $31, 8($sp) stq $1, 72($sp) ==========>>> lda $16, 8($sp) ==========>>> stq $3, 80($sp) ==========>>> mov -1, $17 ==========>>> ldq $19, $$3($gp)!literal!7 lda $18, -256($18) =========>>> lda $20, 72($sp) jsr $26, ($27), for_write_seq_lis!lituse_jsr!5 ldah $gp, ($26)!gpdisp!8 ldq $26, ($sp) lda $gp, ($gp)!gpdisp!8 mov 1, $0 lda $sp, 96($sp) ret ($26) ldah $gp, ($27)!gpdisp!1 unop lda $gp, ($gp)!gpdisp!1 unop ldq $27, for_set_reentrancy($gp)!literal!2 lda $sp, -96($sp) stq $26, ($sp) ldq $16, $$5($gp)!literal!3 jsr $26, ($27), for_set_reentrancy!lituse_jsr!2 ldah $gp, ($26)!gpdisp!4 ldah $18, 388($31) <<<============ lda $gp, ($gp)!gpdisp!4 ldq $27, for_write_seq_lis($gp)!literal!5 mov 12, $1 <<<================== ldq $3, $$7($gp)!literal!6 lda $18, ($18) <<<========= stl $31, 8($sp) lda $16, 8($sp) <<<============= stq $1, 72($sp) <<<============= mov -1, $17 <<<============= stq $3, 80($sp) <<<============= ldq $19, $$3($gp)!literal!7 sll $18, 8, $18 <<<============= lda $20, 72($sp) jsr $26, ($27), for_write_seq_lis!lituse_jsr!5 ldah $gp, ($26)!gpdisp!8 ldq $26, ($sp) lda $gp, ($gp)!gpdisp!8 mov 1, $0 lda $sp, 96($sp) ret ($26)

29 Machine Code for helloworld.f How to Program in Machine Language Directly (1) Write assembly code for the program directly by hand. (2) For each assembly language opcode, look up the associated machine code bit pattern. (3) On the computer console, flip switches to match the machine code. (4) Press the Run button. Actually, on modern computers, programming in machine language directly is just about impossible.

30 Why Not Do Everything in Machine Language? Application Problem Programming in Machine Language Executable Incredibly tedious and ridiculously error-prone! Application Problem Programming in High Level Language Compiling Executable Fun and easy! Not nearly as tedious or error-prone! Why Not Do Everything in Assembly Language? Application Problem Programming in Pentium Assembly Language Can t be run on any other kind of computer. May be completely obsolete in a few years. Compiling for DEC Alpha Executable only for Pentiums Executable for Alphas Application Problem Programming in High Level Language Compiling for Pentium Executable for Pentiums Compiling for SGI/MIPS Executable for SGI/MIPS

31 The Programming Process Formulate Problem Construct Algorithm Choose Programming Language Write Program Compile Bugs? Yes Debug No Run Bugs? Yes No Get an A/Impress Your Boss/Sell for Zillions!

32 A Less Simple Fortran 90 Program!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Program: mynumber!!!!!! Author: Henry Neeman!!!!!! Class: CS Spring 2000!!!!!! Lab: Sec 013 Fridays 2:30pm!!!!!! Description: Asks the user to pick a number within a!!!!!! range, then tells whether the user s number!!!!!! matches the program s.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! PROGRAM mynumber!! Declarations!! No implicitly typed variables. IMPLICIT NONE! Parameter constants! minnum: the user s number should be at least this.! minnum: the user s number should be at most this.! mynum: the number that the computer is thinking of. INTEGER,PARAMETER :: minnum = 1, maxnum = 10 INTEGER,PARAMETER :: mynum = 5! Local variable! yournum: the user s chosen number. INTEGER :: yournum!! Execution!! Tell the user the range to choose from. PRINT *, I m thinking of a number between, minnum, & & and, maxnum,.! Ask for the user s number. PRINT *, What number am I thinking of?! Input the user s number. READ *, yournum! Check whether the number is correct. IF ((yournum.lt. minnum).or. (yournum.gt. maxnum)) THEN! Idiotproofing: if it s outside the range, complain. PRINT *, Hey! That s not between, minnum, & & and, maxnum,! ELSE IF (yournum.eq. mynum) THEN! If it s correct, be amazed. PRINT *, That s amazing! ELSE IF (ABS(yournum - mynum).eq. 1) THEN! If they re within 1, say they re close. PRINT *, Close, but no cigar; I had, mynum,. ELSE! Otherwise, be cruel. PRINT *, Bzzzt! My number was, mynum,. ENDIF END PROGRAM mynumber

33 A Less Simple Fortran 90 Program s Output scarecrow 2% f90 -o mynumber mynumber.f90 Linking: scarecrow 3% mynumber I m thinking of a number between 1 and 10. What number am I thinking of? 0 Hey! That s not between 1 and 10! scarecrow 4% mynumber I m thinking of a number between 1 and 10. What number am I thinking of? 2 Bzzzt! My number was 5. scarecrow 5% mynumber I m thinking of a number between 1 and 10. What number am I thinking of? 4 Close, but no cigar; I had 5. scarecrow 6% mynumber I m thinking of a number between 1 and 10. What number am I thinking of? 5 That s amazing! scarecrow 7%