Trouble Plotting Basic Function

I'm having difficulty getting a function to plot correctly in Matlab. The function is:

f(x) = x^3 - sin(x) - e^x

I've tried using the below but the graph is not how it should appear:

X = -4:0.01:10;
Y = X.^3 - (sin(X)) - (exp(X));
plot(X,Y)

[Sam Chak]

Hi @Kevin

I suggest that you plot each component so that you can clearly see that the cubic function and the exponential function are unbounded, with the latter having a significant impact. Of course, it would be beneficial if you could provide a sketch of the expected plot.

X   = -4:0.01:10;
Y1  = X.^3;
Y2  = sin(X);
Y3  = exp(X);
Y   = Y1 - Y2 - Y3;

tl  = tiledlayout(2, 3);
nexttile
plot(X, Y1), grid on, title('x^{3}')
nexttile
plot(X, Y2), grid on, title('sin(x)')
nexttile
plot(X, Y3), grid on, title('exp(x)')
nexttile([1 3])
plot(X, Y),  grid on, title('y = x^{3} - sin(x) - exp(x)')
xlabel(tl, 'x')

[Sam Chak]

Hi @Kevin

If is a Gaussian distribution function and all three components are appropriately scaled, then the contribution of each function can be observed at different intervals. In the range , the cubic function has little influence. The sine wave affects the overall sinusoidal pattern of the signal, while the Gaussian function has a strong presence at .

X   = -4:0.01:10;
Y1  = 0.002*X.^3;
Y2  = sin(X);
Y3  = exp(-X.^2);
Y   = Y1 - Y2 - Y3;

tl  = tiledlayout(2, 3);
nexttile
plot(X, Y1), grid on, title('0.001 x^{3}')
nexttile
plot(X, Y2), grid on, title('sin(x)')
nexttile
plot(X, Y3), grid on, title('exp(-x^{2})')
nexttile([1 3])
plot(X, Y),  grid on, title('y = 0.001 x^{3} - sin(x) - exp(-x^{2})')
xlabel(tl, 'x')

Answer 1

[Star Strider]

It appears to be coded correctly.

How is it supposed to appear?

X = -4:0.01:10;
Y = X.^3 - (sin(X)) - (exp(X));

figure
plot(X,Y)

Y = X.^3 - (sin(2*pi*X)) - (exp(X));

figure
plot(X,Y)

I thought about multiplying the sin argument by , however that doesn’t siignificantly change the reesul.

.