So, I'll just come out and say that I'm new to C programming. I took an introduction class for it this semester and I'm currently creating a code of my own. The program is meant to calculate the time it would take for two galaxies to merge after meeting. Treating them both as point-masses, here are the inputs: R = distance between the galaxies = 0.45 (kpc) Mtot = total mass of the two galaxies = 3762e39 (kg) v = velocity of the approaching galaxy = 150 (km/s) The program plugs that into the equation for C and T = (2*Pi*v*R^2)/(C*G*Mtot) and outputs the value for T, which comes out to be 1.87 x 10^9. What I'm trying to do with the second part is have the program able to return that T in increments. For example, when T = 1 x 10^9 (1 billion years), then the other galaxy is ___ kpc away, and so on. And I want it to be able to do this starting from the initial R, 0.45 kpc, and ending when R = 0. Here's the code: Code: #include <stdio.h> #include <math.h> double G, T, Mtot, R, v, B, A, C, Pi, distance; int main (void) { G = 6.67e-11; Pi = 3.14159; printf("Enter the combined mass of the systems (kg):"); scanf("%lf", &Mtot); printf("Enter distance between galaxies (kpc):"); scanf("%lf", &R); printf("Enter the relative velocity of the approaching galaxy (km/s):"); scanf("%lf", &v); while (R > 1.0e-21) { C = ((pow(v,2))/2.0) - (G*Mtot)/R; T = (2.0*Pi*v*(pow(R,2)))/(C*G*Mtot); printf("\nWhen T = %d years",T); printf(" then the other galaxy is %f kpc away",R); R=R-0.05; } } It compiles and runs fine, but it returns the T values backwards. As in, it returns that when T = 1.87..., R = 0.45 (the initial R value), when it should be the flipped. R should be 0 when T = 1.87... Could someone tell me how I could essentially reverse the order of the output? Or perhaps point out in my code why it's printing the results this way? Any help would be appreciated. The compiler I use is Cygwin, by the way.
printf("\nWhen T = %d years",T); since T is declared as double use %g instead of %d in the above line of code
