# Error: Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.

조회 수: 1,305(최근 30일)
Dawid Brits 24 Sep 2019
Hi all, Im working on a code that simulates a stock price over two years and then compares it to a strike price (call options). I want to simulate the stock price 3000 for each starting value (30 to 150), then take the average payout (for that particular staring price) and plot that vs the starting price. The idea is that if the final price is higher than the strike price (starting price) you get a payout equal to the difference between the final and strike price, if not you get 0.
I keep getting an error (Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.) gives the error in the line
for S(1, :) = 30 : 150
Here is my code
r = 0.05;
T = 2;
dt = 1/365;
sigma = sqrt(r);
rng('shuffle')
eta = randn(1, 365*T+1);
n_iterations = 3000;
S = zeros(365*T, n_iterations);
for S(1, :) = 30 : 150
n = 1 : n_iterations;
for k = 1 : 365*T
S(k+1, n) = S(k, n) + S(k, n).*r.*dt + sqrt(dt).*sigma.*S(k, n).*eta(k, n);
end
strike = S(1, :);
price = S((365*T + 1), :);
eurocallreturn(strike, price);
avereturn = mean(eurocallreturn);
hold on
plot(strike, avereturn)
xlabel('Price')
ylabel('Return')
end
function R = eurocallreturn(strike, price)
if price > strike
R = price - strike;
else if price <= strike
R = 0;
end
end
end

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### 채택된 답변

Walter Roberson 24 Sep 2019
In MATLAB, the variable immediately after the keyword for must be a simple variable, not indexed in any way -- no () indexing, no {} indexing, no dot indexing. For example it is not permitted to write
for counters.laps = 1 : 20
You will need to rewrite to something like
for Sidx = 30 : 150
S(1, :) = Sidx;
....
end

#### 댓글 수: 2

Dawid Brits 24 Sep 2019
I think that did the trick, however its giving me a different error
Index in position 2 exceeds array bounds (must not exceed 731).
Error in assig5part2b (line 16)
S(k+1, n) = S(k, n) + S(k, n).*r.*dt + sqrt(dt).*sigma.*S(k, n).*eta(k, n);
is this because I'm initializing the vector in the wrong size?
Walter Roberson 24 Sep 2019
It is a problem with you you initialize and use eta which I answered in your other Question.

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### 추가 답변(1개)

Manoj Shukla 1 Apr 2020
Hello,
Email Id:- rsmanojshukla@gmail.com
0.3764
0.5673
0.1168
0.1535
0.6345
Train Accuracy: 83.050847
Expected accuracy (with lambda = 1): 83.1 (approx)
>>
>>
>> submit()
'parts' requires one of the following:
Automated Driving Toolbox
Robotics System Toolbox
Sensor Fusion and Tracking Toolbox
Error in submitWithConfiguration (line 4)
parts = parts(conf);
Error in submit (line 40)
submitWithConfiguration(conf);
Thanks & Regards,
Manoj

#### 댓글 수: 1

Walter Roberson 1 Apr 2020
submitWithConfiguration contains code in which the name parts is used both for a function and as a variable name. With recent changes to MATLAB, MATLAB cannot locate the function. The repair for this is to change submitWithConfiguration to use a different variable name instead of parts .

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