# Question:Why are the level curves wrong when axis mode is switched to log?

## Question:Why are the level curves wrong when axis mode is switched to log?

Maple 2015

Using plot3d(..., style=surfacecontour, ...) or contourplot3d(...) displays wrong level curves when some axis are switched to a log mode.

Example:

 > restart:
 > interface(version)
 (1)
 > X := (0.4000000000e-4*(-R+80.00))/(R*(0.4e-1+M__a)):
 > plot3d(X, R=0..10, M__a=10^0..10^4, style=surfacecontour, color=gold)
 > plot3d(X, R=0..10, M__a=10^0..10^4, axis[2]=[mode=log], axis[3]=[mode=log], style=surfacecontour, color=gold)
 > plots:-display(   plots:-contourplot3d(X, R=0..10, M__a=10^0..10^4, axis[2]=[mode=log], axis[3]=[mode=log], color=red),   plot3d(X, R=0..10, M__a=10^0..10^4, style=surface, color=gold) )
 >

The problem is not dramatic because there is a workaround.

 > restart:
 > interface(version)
 (1)
 > X := (0.4000000000e-4*(-R+80.00))/(R*(0.4e-1+M__a)):
 > fig := plot3d(X, R=0..10, M__a=10^0..10^4, style=surfacecontour, color=gold): Tr  := plottools:-transform((x, y, z) -> [x, log[10](y), log[10](z)]): plots:-display(Tr(fig), axis[2]=[tickmarks=[seq(i=10^i, i=0..4)]], axis[3]=[tickmarks=[seq(i=nprintf("%1.0e", 10.^i), i=-7..-1)]])
 >