Calculating Orbits: Finding Satellite Distance from Earth

[kathrynag]

I am doing a problem with calculating orbits.
The orbit can be expressed in polar coordinates as r=p/(1-ecos(theta)) where r and theta are the distance and angle of the satellite from the center of the earth, p is a paremter where p=1200 km, and e is a parameter representing eccentricity.
I'm supposed to write a program to calculate the distance of the satellite from the Earth as a function of theta if the satellite has an eccentrity of 0, .25, .5, .75, and 1.
Write the program to input values of e and theta. Here is what I have done:

program calculating_orbits
implicit none
real :: r !distance of the satellite from the center of the earth
real :: theta !angle of the satellite from the center of the earth
real, parameter :: p=1200 !parameter specifying the size of the orbit
real :: e !parameter specifying the eccentricity of the orbit
write (*,*) 'This program accepts inputs of theta and e and outputs the
+ value of r=p/(1-e*cos(theta)).'
write (*,*) 'This program will run until a number not in the domain
+ is inputted.'
do
write (*,*) 'Please input a real number.'
read (*,*) e
read (*,*) theta
Now I get stuck. Any hints?

 

[mathmate]

r=p/(1-e*cos(theta))

can you try to write this in fortran and print r as your result?

 

[akshaythegeek]

Few questions in fortran :)
1. Which is the best plotting tool in fortran
2. How to get out put in form of .dat files in fortran
3. Can anyone post a code for calculating floating point operations and finally plotting it..I read so many papers i never able to understand how they plot those

 

[minger]

1. Which is the best plotting tool in fortran

If you're using *NIX, you can use XMGRACE. Typically I just write a file which can be easily read into Excel.

2. How to get out put in form of .dat files in fortran

You can write in any form you want. I don't understand.

3. Can anyone post a code for calculating floating point operations and finally plotting it..I read so many papers i never able to understand how they plot those

OPEN(11,file='output_file.dat',form='formatted')
DO i=1,10
  x = REAL(i)
  y = x**2
  WRITE(11,*) x,y
END DO
CLOSE(11)

 

[akshaythegeek]

What about calculating floating point operation, suppose i have a mac and i am running a program then how to compare two programs ..how to plot graphs between floating point operations ...between these two programs