Yes, Cedric the ZoomLensInterpolation would be good, but might be a bit overkill for this. The ScaleMap class would be another alternative. See the quick example below:
Code:/**
* Logarithmic scale vs. linear scale example
* Requires toxiclibscore-0014 or newer: http://toxiclibs.org/
*
* @author toxi
*/
import toxi.math.*;
float expectedMinValue=1;
float expectedMaxValue=800;
ScaleMap linearMap;
ScaleMap logMap;
size(1000,200);
smooth();
// create 2 scale maps
// parameters: in_min, in_max, out_min, out_max
logMap=new ScaleMap(log(expectedMinValue),log(expectedMaxValue),0,width);
linearMap=new ScaleMap(expectedMinValue,expectedMaxValue,0,width);
for(float i=expectedMinValue; i<expectedMaxValue; i+=10) {
// get log scale value
float x1=(float)logMap.getMappedValueFor(log(i));
stroke(0);
line(x1,0,x1,50);
// get linear mapped value
float x2=(float)linearMap.getMappedValueFor(i);
line(x2,150,x2,200);
// draw connection line
stroke(0,50);
line(x1,50,x2,150);
}