How can i plot this function with factorial?

I would like to have the following function plotting:

lap = (3*factorial(x)-1)./(120*10^(12));

xValues = linspace(0,1,20);
plot(xValues, semilap(xValues));

I get the following error message:

"Array indices must be positive integers or logical values."

I would also be very grateful if someone could tell me how to plot the Y-axis logarithmically in this case.

[VBBV]

x = 4; % input vector same size as xValues
lap = (3*factorial(x)-1)./(120*10^(12));
xValues = linspace(0,1,20);
semilogy(xValues, (lap)); % semilogy 

Value of x here is shown as e,g,

Answer 1

[Rik]

If you want to plot a function, you should do so explicitly:

lap = @(x)(3*factorial(x)-1)./(120*10^(12));
xValues = round(logspace(0,1,20));%round to make sure the input to factorial is interger-only
semilogy(xValues, lap(xValues))

Answer 2

[Steven Lord]

You haven't shown us what semilap is. If you intended for that to be the expression in lap evaluated at the points in xValues, you need to make lap a function or a function handle (which could be anonymous.) However:

lap = @(x) (3*factorial(x)-1)./(120*10^(12));

xValues = linspace(0,1,20);
plot(xValues, lap(xValues));

Error using factorial (line 20)
N must be an array of real non-negative integers.

Error in solution (line 1)
lap = @(x) (3*factorial(x)-1)./(120*10^(12));

the factorial function is only defined for real non-negative integer values and xValues contains non-integer values. You could use the gamma function instead.

As for plotting logarithmically, see the semilogy function (or semilogx if you want just the X axis to be in logarithmic scale or loglog if you want both logarithmic.)