defining the range of an inverse function

To plot function y1=3*exp(x./3+1); between x=[0:0.01:1]; using the hold on and axis equal add the inverse y2=3*log(x./3)-3; on the same graph between x values that come from the range of the original F(x) being x2=[3e^1/3:0.01:3e^4/3];, keep getting the error ;vectors must be same length, is there a better way I can define x2?

Thanks in advance for any assistance.

>> plot(x,y1)
>> hold on
>> axis equal
>> plot(x1,y2)
Error using plot
Vectors must be the same length.

Answer 1

[Stephen23]

MATLAB does not support implicit multiplication, which means you cannot write multiplication as 3e, you must write 3*e together with the multiplication symbol (although the letter e can be used for creating numbers using E-notation scientific numbers). And to get the value of Euler's number e you should use exp(1), as e is not defined with this value. So with these various changes we can define x2 as:

x2 = 3*exp(1)^1/3:0.01:3*exp(1)^4/3;

Which means the whole code now runs without error:

x1 = 0:0.01:1;
y1 = 3*exp(x1/3+1);
x2 = 3*exp(1)^1/3:0.01:3*exp(1)^4/3;
y2 = 3*log(x2/3)-3;
plot(x1,y1)
hold on
axis equal
plot(x2,y2)

Of course it is up to you to decide if the calculation itself is correct.

[Joel Kelly]

Excellent, that helped me sort that one out, much appreciated.