The line in yellow and sky blue gives the nearest x for each y, with blue on cells that are also the nearest y for their x, and spots in other colors where the x is within 0.05 unit of true (and one in a greyed yellow barely outside that standard; and all of these would be blue cells if this special spot color did not override). The 26/15 one is the only one so far accurate enough that its harmonics are within spec too (shown in purple).