Program to approximate e^x using the Taylor Series

I am attempting to write a function called expSeries which uses another function factFunc to evaluate e^x. I have already written the function factFunc, as shown below:

function fact = factFunc(n) 

    f = 1;

    for a = 1:b
        f = f*a;      
    end

    fact = f;

end

I am now attempting to write the function expSeries which evaulates e^x using the Taylor series. This is what I have so far:

function expo = exponentialFunc(x) 

terms = input('Enter the number of terms');
b = 0;
for i = 1:terms
        b = x/factFunc(terms);
end
expo = b;
end

And in the main program, I have

n = exponentialFunc(4);
disp(n);

Where in this instance I am trying to find e^4. However, the output is not what expected. Does anyone have any idea where I am going wrong?

Answer 1

[madhan ravi]

might help:

https://www.mathworks.com/matlabcentral/answers/410372-i-need-help-with-a-taylor-series-approximation-of-e-x#answer_328853

Answer 2

[Walter Roberson]

Taylor series involve the sum of terms but your

 for i = 1:terms
   b = x/factFunc(terms);
 end

Is overwriting all of b each cycle.

[Torsten]

And in "factFunc", you must use "n" instead of "b".

[Walter Roberson]

? You would use i not n

[Torsten]

for a = 1: *b*

should read

for a = 1: *n*

Best wishes

Torsten.