Graphing a user input function between limits

So what I'm trying to do is plot the user input function between the two plots (pltA and pltB) as number of times determined by the numberofplots input by user. With what I have now it does indeed calculate all the values of y and x between A and B for the default number of iterations (100) but when it plots them it only plots the first value and continues on with the program. Any ideas?

pltA = get(handles.txtA,'String');

pltA = str2num(pltA);

pltB = get(handles.txtB,'String');

pltB = str2num(pltB);

numberofplots = get(handles.txtPlot,'String');

numberofplots = str2num(numberofplots);

intIndex = (pltB - pltA) / numberofplots

intplotiteration = 1

strX = pltA

        while abs(intplotiteration) <= numberofplots

            strX = strX

            sngX = num2str(strX)

            sngX = ['(' sngX ')']

            strFx = strrep(strEquation,'x',sngX)

            sngPlot = eval(strFx)

            intIndex = pltA + intIndex

            intplotiteration = intplotiteration + 1

            plot(strX,sngPlot)

            hold all

        end