Find Areas of a Series of XY pairs

//  FindXYAreas(xList, yList, destWaveName)
//  Finds areas of a series of XY pairs.
//  xList is a semicolon-separated list of X wave names. If xList contains only one
//  wave name then that wave is used as the X wave for all XY pairs.
//  yList is a semicolon-separated list of Y wave names.
//
//  Example:
//      Make/O/N=6 xData=x, yData0=x, yData1=x+1, yData2=x+2
//      String yList = WaveList("yData*", ";", "")      // "yData0;yData1;yData2;"
//      FindXYAreas("xData;", yList, "xyAreas")
//      Edit xyAreas
Function FindXYAreas(xList, yList, destWaveName)
    String xList                // Semicolon-separated list of x waves
    String yList                // Semicolon-separated list of y waves
    String destWaveName // Name for output wave. This wave is OVERWRITTEN.

    Variable numXWaves = ItemsInList(xList)
    Variable numYWaves = ItemsInList(yList)
   
    Make/O/N=(numYWaves) $destWaveName
    Wave dest = $destWaveName           // Make wave reference
   
    Variable i
    for(i=0; i<numYWaves; i+=1)
        String xName
        if (numXWaves == 1)
            Wave xw = $StringFromList(0, xList)     // Use the same X wave every time
        else
            Wave xw = $StringFromList(i, xList)     // Use a different X wave every time
        endif
        String yName = StringFromList(i, yList)
        Wave yw = $yName
        Variable result = areaXY(xw, yw)
        dest[i] = result
    endfor
End