# why matlab2018a gives "vpa(int( exp((t-360​).*[0,1e-1​6,1e-15,1e​-14,1e-13,​1e-12,1e-1​1]) , t, 0,360 ))=[ 360.0, 0, 0, 0, 256.0, 368.0, 360.0]"??

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Jiyuan Liu on 19 Jun 2018
Commented: Jiyuan Liu on 11 Jul 2018
Hi all,
Weird the matlab 2018a calculate the below code--
syms t;
vpa(int( exp((t-360).*[0,1e-16,1e-15,1e-14,1e-13,1e-12,1e-11]) , t, 0,360 ))
resulting in
[ 360.0, 0, 0, 0, 256.0, 368.0, 360.0]
Do you guys have expertise helping avoid this happening?
thanks a lot
J
Ameer Hamza on 19 Jun 2018
I get the following output on R2018a and R2017b.
syms t;
vpa(int( exp((t-360).*[0,1e-16,1e-15,1e-14,1e-13,1e-12,1e-11]) , t, 0,360 ))'
ans =
360.0
359.99999999999352000000000231367
359.99999999993520000000000783383
359.99999999935200000000077761612
359.99999999352000000007775999991
359.99999993520000000777599999918
359.99999935200000077759999930015
Are you sure that you are running exactly the same line?
Jiyuan Liu on 11 Jul 2018
thanks Ameer, i've got the reason for the earlier error i got-- I put digits(5) (or maybe digits(3)) before these sentences. And after I reset it to 32 or 64, the results are normal again.

Siwan Yang on 22 Jun 2018
Hello Jiyuan,
I couldn’t reproduce your result in both R2018a and R2015a. Here is what I got: [ 360.0, 359.99999999999352000000000231367, 359.99999999993520000000000783383, 359.99999999935200000000077761612, 359.99999999352000000007775999991, 359.99999993520000000777599999918, 359.99999935200000077759999930015]
Please try changing different data type and see if you still have the issue.
Thanks,
Siwan
Jiyuan Liu on 11 Jul 2018
thanks Siwan, R2018a and R2015a work both fine. I put digits(5) (or maybe digits(3)) before these sentences, which leads to the weird results.

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