+#undef OLD_GAIN_MATH
+#define OLD_GAIN_MATH
+
+static inline double
+gain_to_slider_position (ARDOUR::gain_t g)
+{
+ if (g == 0) return 0;
+
+#ifndef OLD_GAIN_MATH
+ /* Power Law With Exponential Cutoff 2D, fit to data from TC Spectra
+ console (image of fader gradations
+
+ y = C * x(-T) * exp(-x/K)
+
+ C = 8.2857630370864188E-01
+ T = -5.1526743785019269E-01
+ K = 7.8990885960495589E+00
+
+ */
+
+ return 8.2857630370864188E-01 * pow(g,5.1526743785019269E-01) * exp (-g/7.8990885960495589E+00);
+#else
+ return pow((6.0*log(g)/log(2.0)+192.0)/198.0, 8.0);
+#endif
+}
+
+static inline ARDOUR::gain_t
+slider_position_to_gain (double pos)
+{
+ if (pos == 0.0) {
+ return 0.0;
+ }
+
+#ifndef OLD_GAIN_MATH
+ /* 5th order polynomial function fit to data from a TC Spectra console
+ fader (image of fader gradations).
+
+ y = a + bx1 + cx2 + dx3 + fx4 + gx5
+
+ a = -1.1945480381045521E-02
+ b = 1.5809476525537265E+00
+ c = -1.5850710838966151E+01
+ d = 6.1643128605961991E+01
+ f = -8.5525246160607693E+01
+ g = 4.1312725896188283E+01
+
+ */
+
+ double p = pos;
+ double g = -1.1945480381045521E-02;
+
+ g += 1.5809476525537265E+00 * pos;
+ pos *= p;
+ g += -1.5850710838966151E+01 * pos;
+ pos *= p;
+ g += 6.1643128605961991E+01 * pos;
+ pos *= p;
+ g += -8.5525246160607693E+01 * pos;
+ pos *= p;
+ g += 4.1312725896188283E+01 * pos;
+
+ return g;
+#else
+ /* XXX Marcus writes: this doesn't seem right to me. but i don't have a better answer ... */
+ if (pos == 0.0) return 0;
+ return pow (2.0,(sqrt(sqrt(sqrt(pos)))*198.0-192.0)/6.0);
+#endif
+}
+#undef OLD_GAIN_MATH
+
+double gain_to_slider_position_with_max (double g, double max_gain = 2.0);
+double slider_position_to_gain_with_max (double g, double max_gain = 2.0);