W02 D01 LAB Computational Methods

7/27/2019 W02 D01 LAB Computational Methods

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(C++)PROGRAMMING

IN PHYSICS


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Material(s) we need

A text editor (gedit, or kate)

Terminal or konsole


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Say Hi to simple Hello World Program

/*

Program: helloworld.cc

Author: Giovanni J Paylaga

Date created: 6/27/2013 12:30PM

Date modified: 6/27/2013 12:30PMNOTE: program simply prints out hello world

*/

#include

int main() {

std::cout


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Say Hi to simple Hello World Program

/*

Program: helloworld.cc



Date modified: 6/27/2013 12:30PMNOTE: program simply prints out hello world

*/

#include

int main() {

std::cout


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Build and Run the Hello World Program

Build Command:

g++ helloworld.cc o helloworld

Run Command:./helloworld

g++ = C++ compilerhelloworld.cc = source file

helloworld = executable program


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Build and Run the Hello World Program

Build Command:


Run Command:./helloworld

g++ = C++ compilerhelloworld.cc = source file

helloworld = executable program

-o option createsexecutable file


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What is the difference between:

int main() {}

int main(int argc, char** argv) {}

If a program is going to ignore

command line arguments, choose the

first line.Choose the second line if the

program needs to process line

arguments.


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int main(int argc, char** argv) {}

argc = argument countargv = argument vector

Similar toint main(int num_args, char** arg_strings) {}


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#include

int main(int argc, char** argv) {

std::cout


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#include


std::cout


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/*Program: masstoenergy.cc



Date modified: 6/27/2013 12:30PMNOTE: converts mass to energy, E = m*c^2

*/

#include


float m, E; // variable m = mass, E = energy

const float c = 3e8; // c = speed of light in m/s

m = atof(argv[1]); // atof converts string into float

E = m*c*c;std::cout


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/*Program: masstoenergy.cc



Date modified: 6/27/2013 12:30PMNOTE: converts mass to energy, E = m*c^2

*/

#include


float m, E; // variable m = mass, E = energy

const float c = 3e8; // c = speed of light in m/s

m = atof(argv[1]); // atof converts string into float

E = m*c*c;std::cout


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Header, Source, & main file

Suppose we want a program thatcalculates the dot product of twovectorsAand B.

Needed Files:

MAIN: VectorDotProduct_main.cc

HEADER: CalculateDotProduct.hh

SOURCE: CalculateDotProduct.cc

Article: Header and Includes: Why and How,

Link: www.cplusplus.com/forum/articles/10627/
http://www.cplusplus.com/forum/articles/10627/http://www.cplusplus.com/forum/articles/10627/


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Header, Source, & main file

Suppose we want a program thatcalculates the dot product of twovectorsAand B.

Needed Files:




Article: Header and Includes: Why and How,

Link: www.cplusplus.com/forum/articles/10627/

Interface &

Implementation

V t D tP d t i
http://www.cplusplus.com/forum/articles/10627/http://www.cplusplus.com/forum/articles/10627/


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/*

Program: VectorDotProduct_main.cc



Date modified: 6/27/2013 12:30PM

NOTE: calculate the dotproduct of two vectors

*/

#include


// define two vectors A and B

const int ndim = 3; // in 3-dimenasions

double vectorA[ndim] = {1.0, 1.5, 2.0};

double vectorB[ndim] = {3.0, 4.0, 5.0};

double dotproduct = 0.0;

// calcuate the dotproduct

for(int i = 0; i < ndim; i++) {dotproduct += vectorA[i] * vectorB[i];

}

// print out results

std::cout


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/*






*/

#include








for(int i = 0; i < ndim; i++) {dotproduct += vectorA[i] * vectorB[i];

}


std::cout


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/*






*/

#include

#include CalculateDotProduct.hh








dotproduct = CalculateDotProduct(vectorA, vectorB);


std::cout


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VectorDotProduct_main.c/*Program: VectorDotProduct_main.cc





*/

#include









dotproduct = CalculateDotProduct(vectorA, vectorB);


std::cout


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CalculateDotProduct.h/*

Program: CalculateDotProduct.hh


Date created: 6/27/2013 12:30PMDate modified: 6/27/2013 12:30PM

NOTE: header file that calculate the dotproduct of two vectors

*/

#ifndef _CALCULATE_DOT_PRODUCT_HH

#define CALCULATE_DOT_PRODUCT_HH

double CalculateDotProduct(double *vector1, double *vector2);

#endif


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CalculateDotProduct c


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CalculateDotProduct.c/*

Program: CalculateDotProduct.cc



NOTE: source file that calculate the dotproduct of two vectors

*/


double CalculateDotProduct(double *vector1, double *vector2) {


double result = 0.0;

result = CalculateDotProduct(vectorA, vectorB);

return result;

} # end of CalculateDotProduct

CalculateDotProduct c


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CalculateDotProduct.c/*

Program: CalculateDotProduct.cc



NOTE: source file that calculate the dotproduct of two vectors

*/


double CalculateDotProduct(double *vector1, double *vector2) {


double result = 0.0;

result = CalculateDotProduct(vectorA, vectorB);

return result;

} # end of CalculateDotProduct

Implementation


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Running our Program

Now we have the Needed Files:




Enter these commands:

g++ -c VectorDotProduct_main.ccg++ -c I ./ CalculateDotProduct.cc

g++ VectorDotProduct_main.o CalculateDotProduct.o o DotProduct


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Running our Program








First line will createan object file

VectorDotProduct_main.o(a.k.a. library file)

NOTE: there is noexecutable file yet.


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Running our Program








second line will compilesource file into an object

file CalculateDotProduct.o

NOTE: compiler will searchfor the header file

HOW? By adding -I ./

Where ./ = directory where your

header is.


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Running our Program








Last line will link theexecutable program

DotProduct to the objectfiles (*.ofiles)

Note: -o lets you generatethe executable file

You can then run it:

./DotProduct


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Make you life easier by using Makefiles

Makefilesspecial format files utilized by

make to automatically create and

manage applicationsCommand: make -f yourMakeFile

Example: place this inside yourMakeFile:all:


Then type/execute the command


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MakefilesFormat:

[target] = dependencies

[tab] system command

Example:

all:



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MakefilesFormat:

[target] = dependencies

[tab] system command

Example: UTILIZiNG dependencies

all: helloworld

helloworld: main.o helloworld.o

g++ main.o hello.o o helloworld

main.o: main.ccg++ -c main.cc

helloworld.o: helloworld.ccc

g++ -c helloworld.cc

clean:

rm rf *o helloworld


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Make you life easier by using MakefilesUsing variables $(VAR) and comments # or /**/

# I am a comment, let variable CC = compiler to useCC = g++

/* CFLAGS will be the options thatll be passed to the

compilers */

CFLAGS = -c Wall Wno-deprecated

all: helloworld

helloworld: main.o helloworld.o

$(CC) main.o hello.o o helloworld

main.o: main.cc$(CC) $(CFLAGS) main.cc

helloworld.o: helloworld.ccc

$(CC) $(CFLAGS) helloworld.cc

clean:

rm rf *o helloworld

Recall our VectorDotProduct program


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Recall our VectorDotProduct program# Makefile# Author: Giovanni J Paylaga

CC = g++

CFLAGS = -cWall

Wno-deprecated

SRCS = VectorDotProduct_main.cc CalculateDotProduct.cc

OBJS = VectorDotProduct_main.o CalculateDotProduct.o

LIBS = -L ./

INCS = -I ./

PROG = DotProduct

all:$(PROG)

$(PROG):$(OBJS)$(CC) $(CFLAGS) $^ $(LIBS) o $@

.cc.o:

$(CC) $(CFLAGS) $(INCS) -c $< -o $@

clean:

rm rf *.o $(PROG)



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CC = g++

CFLAGS = -cWall

Wno-deprecated



LIBS = -L ./

INCS = -I ./

PROG = DotProduct

all:$(PROG)


.cc.o:


clean:

rm rf *.o $(PROG)

$^ = all dependencies

Equivalent to

VectorDotProduct_main.o CalculateDotProduct.o



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CC = g++

CFLAGS = -cWall

Wno-deprecated



LIBS = -L ./

INCS = -I ./

PROG = DotProduct

all:$(PROG)


.cc.o:


clean:

rm rf *.o $(PROG)

$@ = target name

Equivalent to

$(PROG) = DotProduct



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CC = g++

CFLAGS = -cWall

Wno-deprecated



LIBS = -L ./

INCS = -I ./

PROG = DotProduct

all:$(PROG)


.cc.o:


clean:

rm rf *.o $(PROG)

$< = first dependency.cc.o = This is a suffix

replacement rule for building.os from .ccs.

It uses automatic variables $


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Exercises: Write a program that will calculate the vertical and horizontal

positions (in meters) and components of the velocity vector(in m/s) of a projectile at any given time (value of time is asked at

run time). Use the following conditions:

Write a program to sum the series:

2 1(1)

sin()

= let n = 100, x=0.5

Write a program that calculates the dot product of n-dimensionalvectors. It asks the user at run time for two vectors anddetermines if they have the same dimensions. It informs the userabout the dimension of each vector and prints out their dotproduct.

y0 = 5m x0 = 0 m

v0 = 20m/s theta= 30o.

Assignment


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Assignment Write a program that will calculate the mean and standard

deviation of a set of data. It asks the user at run time the number

of data points.

W02 D01 LAB Computational Methods

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