Mathcad won't be able to provide a symbolic solution because it cannot decide on the different branches of min, max or an if statement with a variable, symbolic argument
For a numeric solution you may use a simple solve block. In the example you provided it works OK var values of d up to 2. z(d)=1 for d>2, so z is not bijective outside the interval you have chosen and so the inverse can't works. rev(z) would yield 1 for z=1.
In your final application one problem could be that a single, constant guess value for d (in my sheet I had chosen d=1) does not work for the whole range of z-values provided. But we'll deal with this issue when we get to it.
