Error in Matlab Coder: Index exceeds array dimensions - arrays

Question

I am trying to convert .m script to C++ using MATLAB Coder.
function P=r_p(1,var1,var3)
p=[[3,7]
[10,15]
[6,19]
[21,19]
[43,11]
[969,2]
[113,9]
[43,59]
[21,15]
[6,15]
[10,18]
[3,15]];
tmax=sum(p(:,1))+41;
coder.varsize('x');
x=ones(9,11).*[0:10:100]; % getting error in this line: [9x11]~=[1x11]. Since size of x is varying in for loop, so i should tell coder that it is variable size, So I used Varsize
for t=11:tmax
a1=(rand-0.5)*1;
a9=(rand-0.5)*1.25;
a2=(rand-0.5)*1.5;
a8=(rand-0.5)*1.75;
a3=(rand-0.5)*2.0;
a7=(rand-0.5)*2.25;
a4=(rand-0.5)*2.5;
a6=(rand-0.5)*2.75;
a5=(rand-0.5)*3;
x(1,t+1)=x(1,t)+a1;
if x(1,t+1)<(100-var1) || x(1,t+1)>(100+var1) % loop 1: x(1,11)+a1 value is is writing to x(1,12) So coder gives error "Index exceeds array dimensions. Index value 12 exceeds valid range [1-11] of array x".
x(1,t+1)=x(1,t); % In matlab it works fine, but coder throws error.
end
end
My question is Let say loop 1,
x(1,12)= x(1,11)+a1 In matlab this assignment works fine, but when converting it is throwing error " Index exceeds array dimensions. Index value 12 exceeds valid range [1-11] of array x" As I declared x as variable size coder should assign x(1,11)+a1 value to x(1,12) but it is not doing, instead throwing error. Why?
Since t is looping for 1289, if I specify bounds for x like
coder.varsize('x',[1290,1290],[0,0]) then Coder gives error in other part of the code i.e dimensions doesn't match. Ofcourse it should because dimension of x doesn't match with [ones(12,9)p(1,2)/9;(P_1s+var3/100P_1s.*randn(size(P_1s))/2)/9;zeros(30,9)].
is declaring x as variable size is correct step or not? if yes then what should be the work around for "index exceeds array dimensions error"
Please Let me know, what am I missing to convert it to C++ code

Answer 1

MATLAB Coder doesn't support 2 things you're using here: implicit expansion and growing arrays by assigning past the end of a dimension.
For implicit expansion, you can use:
x=bsxfun(#times,ones(9,11),[0:10:100]);
Assigning past the end of an array in MATLAB will grow the array. That's an error in Coder. There are 2 ways to overcome this:
Allocate your array to have the right number of elements up front
Use concatenation to grow an array: x = [x, newColumn]
In this example, you know tmax so I'd suggest just changing the allocation of x to have the right number of columns up front:
% Current initial value
x=bsxfun(#times,ones(9,11),[0:10:100]);
% Extra columns - please check my upper bound value
x=[x, zeros(9,tmax)];