I've been trying to implement Tobler's hiking equation in script. The equation goes:
W is walking speed,
S is slope in degrees.
The list of slopes is:
k7=[-1.0312126698879267, 1.1457628381751035, -3.890124404061796, -0.6875278121450912, 0.0, -1.7820676357665195, -1.0532676344873988, 1.7010978323487986]
And my code is:
for f in k7: tob=6*math.expm1(-3.5*abs(f+0.05)) k8.append(tob)
Which should be right, but the results are:
k8=[-5.80650137556095, -5.908682283616555, -5.999991269395487, -5.355698099597122, -0.963257875384756, -5.986024888143845, -5.8208760494265395, -5.986925387994366]
First, they are negative and they shouldn't be, second, notice that the slopes are very similar and so should be the results but notice the fifth element of the results! When I tried this with math.exp I got something completly different and also totally wrong.
I know that this should be very simple but I cant figure it out.
Have I missed something in the equation or is there some trick that I should know about.
I would be really grateful for your help.