I want to plot certain function given by:
for certain interval of x [0.5,1] then I want to use the graph to get values of x that corresponds to certain values of Y
Typically, you would probably use a datastep that contains a loop for X between 0.5 and 1 at whatever step count you want. Then, you can plot the X and Y values on the graph. Are there any other particular requirements you have for your graph?