Patent ID: 7805251

Claim:
A method for executing a computer readable program on a computer, the method comprising: receiving a first line, described by y 1 (x)=m 1 x+B 1 , and a second line, described by y 2 (x)=m 2 x+B 2 , to be joined at a junction location to provide a reference curve, where m 1 is the slope of the first line, B 1 is the y-intercept of the first line, m 2 is the slope of the second line, and B 2 is the y-intercept of the second line; selecting the y-intercept, B 1 , to satisfy B 1 =(m 2 −m 1 )x 0 +B 2 ; calculating the reference curve representing the first line and the second line joined at the junction location according to y(x)=Y 1 (x)+Y 2 (x), where Y 1 ⁡ ( x ) = W 1 ⁢ y 1 ⁡ ( x ) , Y 2 ⁡ ( x ) = W 2 ⁢ y 2 ⁡ ( x ) , W 1 ⁡ ( x ) = 1 1 + e ( x 0 - x ) ⁢ log ⁢ ⁢ 10 w , ⁢ W 2 ⁡ ( x ) = 1 1 + e ( x - x 0 ) ⁢ log ⁢ ⁢ 10 w , x is a variable location on the x-axis, x 0 is the junction location, w is a width parameter controlling the junction sharpness, and W 1 +W 2 =1; and outputting the reference curve for storage or display.