# n O_2 bei z=0km
n := 5.3e18;

# lambda = 140nm:
eq1 := z1 = H*ln(sigma1*n*H/(2*ln(10)));
sigma1 := 10e-17;
z1 := 105*1000*100;
H := solve(eq1,H);

# H in km
H/1000/100;

# lambda = 210nm:
eq2 := z2 = H*ln(sigma2*n*H/(2*ln(10)));
sigma2 := 1.5e-23;

# ausrechnen von z2 in km:
evalf(eq2)/1000/100;

Ausgaben von Maple:
    |\^/|     Maple 9 (IBM INTEL LINUX)
._|\|   |/|_. Copyright (c) Maplesoft, a division of Waterloo Maple Inc. 2003
 \  MAPLE  /  All rights reserved. Maple is a trademark of
 <____ ____>  Waterloo Maple Inc.
      |       Type ? for help.
> # n O_2 bei z=0km
> n := 5.3e18;
                                                                19
                                                    n := 0.53 10

>
> # lambda = 140nm:
> eq1 := z1 = H*ln(sigma1*n*H/(2*ln(10)));
                                                                     19
                                                      0.2650000000 10   sigma1 H
                                     eq1 := z1 = H ln(--------------------------)
                                                                ln(10)

> sigma1 := 10e-17;
                                                                  -15
                                                 sigma1 := 0.10 10

> z1 := 105*1000*100;
                                                    z1 := 10500000

> H := solve(eq1,H);
                                                   H := 582652.1786

>
> # H in km
> H/1000/100;
                                                      5.826521786

>
> # lambda = 210nm:
> eq2 := z2 = H*ln(sigma2*n*H/(2*ln(10)));
                                                                           25
                                                            0.1544028274 10   sigma2
                                 eq2 := z2 = 582652.1786 ln(------------------------)
                                                                     ln(10)

> sigma2 := 1.5e-23;
                                                                  -22
                                                 sigma2 := 0.15 10

>
> # ausrechnen von z2 in km:
> evalf(eq2)/1000/100;
                                                   z2
                                                 ------ = 13.45001584
                                                 100000

>