i want to substract very large value from small value in matlab?

small value = 2.3654

large value = 6.7843e+130

Answer = small value - large value

try to find the substraction but every time i got answer -6.7843e+130.

Answer 1

[madhan ravi]

-6.7843e+130 is just a scientific notation of -6.7843*10^130 ,because the number is really huge matlab shows them as such.

[GHUFRAN AHMAD KHAN]

yes number is so large due to this my result affected.actually i have matrix of order 500X5 for both in which first matrix has small value and second matrix has very large value. due to this every time it give same result.so any good solution to find actual answer.

[Walter Roberson]

The only "good solution" is to write the software to avoid needing to work with values of substantially different magnitude.

That said, a work-around is to use the Symbolic Toolbox to do the calculation after having set digits(150) or so. This will affect performance.

[madhan ravi]

Thank you sir Walter :-)

[GHUFRAN AHMAD KHAN]

i have already symbolic toolbox but still problem could not resolved.

[Walter Roberson]

>> digits(135)
>> smallvalue = sym('2.3654')
smallvalue =
2.3654
>> largevalue = sym('6.7843e+130')
largevalue =
67843000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000.0
>> answer = smallvalue - largevalue
answer =
-67842999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999997.6346