error with indices and vectors

i= 7.5;
A= 300000;
P= 8000;
n=[6:6:60]';
B= A(1+i/12).^n-(P/(i/12)).*((1+i/12).^n-1);

table(n, B)

Array indices must be positive integers or logical values.

can someone help me with this error please?

Answer 1

[Walter Roberson]

MATLAB has no implied multiplication.

A(1+i/12) is syntactically always either a request to execute a function indicated by A with parameter 1+i/12, or else a request to index array A at location 1+i/12 .

As we can see a definition for the variable A, we know that in this case it must be a request to index A at 1+i/12 . But i is 7.5 and 1+i/12 will definitely not be a positive integer, so that is not valid indexing.

If you want to multiply A and (1+i/12) then you need to explicitly multiply, using either the .* or * operator.

[Montserrat López Vargas]

thank you so much!

Answer 2

[Image Analyst]

A is not a vector so there is no (1 + 1/12)th element of it. A is a scalar. Maybe you meant A * (1 + i/12)???

i= 7.5;
A= 300000;
P= 8000;
n=[6:6:60]'
B= A * (1+i/12).^n-(P/(i/12)).*((1+i/12).^n-1)
t = table(n, B)

t =

10×2 table

n B

__ __________

6 5.301e+06

12 9.7383e+07

18 1.7929e+09

24 3.3012e+10

30 6.0783e+11

36 1.1192e+13

42 2.0608e+14

48 3.7944e+15

54 6.9866e+16

60 1.2864e+18