Strings have a specific length and individual characters within the string are referred to by position, the left most character at position 1, etc. In Fortran characters may be treated individually or as contiguous strings. Character handling is very important in numeric applications as the input or output of undocumented numbers is not very user friendly.

This type is used when the data which is being manipulated is in the form of characters and words rather than numbers. In the previous chapter the intrinsic numeric types real and integer were introduced, a third intrinsic type character is presented in this section. Alternatively you could use arbitrarily low/high values for your f_min f_max but then you will be wasting a lot of points and your error will be bigger.Introduction to Fortran 90, Character Processing, QUB The Queen's University of Belfast Print*, (f_max-f_min)*(b-a)*(real(Nin)/Nmc)Īll of this, you could then enclose it in an outer do loop summing the (f_max-f_min) (b-a)(real(Nin)/Nmc) and in the end printing its average.įor this example, what you do is essentially creating an enclosing box from a to b (x dimension) and from f_min to f_max (y dimension) and then doing a sampling of points inside this area and counting the points that are in the function (Nin).Obviously you will have to know the minimum (f_min) and maximum (f_max) value of your function in the range. here's one example that visualizes it pretty niceĮDIT: Second way, that is the same as the Pi method: Nin=0 !Number of points inside the function (under the curve)

There's lots of stuff on the internet for this. Then just divide with Nmc, to find the average and then multiply with (b-a). Then do this lots of times (Nmc times), and calculate the sum. So, all you have to do is generate a random number in the range and then calcualte the value of your function for this x. So, finally, we get that the integral should be: (this g(x) is a uniform probability distribution of the variable x in ). Print*, (b-a)*(SUM/Nmc) !final result of your integral

EDIT: SUM is also an instrinsic function in Fortran so don't call your variable this, I named it so, to illustrate its purpose SUM=SUM+f(x) !summing all values of f(x). X=a+x*(b-a) !converting x to be in range Integer, parameter:: a=1, b=5, Nmc=10000000 !a the lower bound, b the upper bound, Nmc the size of the sampling (the higher, the more accurate the result)Ĭall RANDOM_NUMBER(x) !generating random number x in range I will write the code first and then explain: Program integral

Fortran program for area of circle