Outrageous values when printing out a function

I'm trying to print out a function with defined variables,

vcx = sol(1)*exp(root0*x)+ sol(2)*exp(root1*x);

when testing, I try

fprintf( "%de ^(%d t) + %de ^(%d t)\n",sol(1), root0, sol(2), root1);

the result is

7e ^(-1.866025e+00 t) + -2e ^(-1.339746e-01 t)

these are the values i expected -- 7 for sol(1), -1.866... for root0, -2 for sol(2), and -0.13397... for root1.

However, fprintf("%s", vcx) obtained

(222119821791395497*exp(-(8403831313147477*t)/4503599627370496))/31201853486215849 - (66110554360316252*exp(-(2413471766374059*t)/18014398509481984))/31201853486215849

why is this? This doesn't make any sense. I double checked and root0 and root1 didn't change at least, so what's up with this insane print out?

notice:

I tried solve(vct,x) but this didn't work because the vct isn't an equation.

I also tried solx = solve(solution,x)

where solution = vct == sol(1)*exp(root0*x)+ sol(2)*exp(root1*x);

but this didn't work either.

(solution became 0)

Answer 1

[Mark Sherstan]

Try solving using symbolics and then simplify the expression and see if the error repeats. This would also be a good use for MATLAB's live editor. It appears that MATLAB is simplifying your answer in terms of integers instead of floats.

Answer 2

[seldiora]

I tried solve(vct,x) but this didn't work because the vct isn't an equation.

I also tried solx = solve(solution,x)

where solution = vct == sol(1)*exp(root0*x)+ sol(2)*exp(root1*x);

but this didn't work either.

Answer 3

[Walter Roberson]

vpa(vcx)