... characters. Fortran character variables are very different from C character strings. Each Fortran character variable can have its own length, and it doesn't have to be 1. It's not an array of 100000000000000000000 elements. (I should have used a length that is easier to type, ;() The X(I:I) notation means the Ith character. In general, you can use X(I:J) to mean all of the characters ...

.... If you looked at a certain length on pi, and with length I mean width, and you would think in the neighborhood of 10^20. you could line them up: 100000000000000000000.0000000000000000 31415678888886666444.9890809888809088 and forget about the decimal point, which is the same as multiplying by ten to the eightteen. Then subtract. Keep on subtracting off the largest pi you can. ...

... to generate code equivalent to DO I = L,M DO N = J,K A(N,I) = 0 ENDDO**2 If the dimensions of A are [1000000000000000,2] that's good; if they're [2,100000000000000000000] the DO overhead in the inner loop dominates everything. 3.5) Maybe the compiler can prove that J:K,L:M runs over the entire array, in which case it can use a single equivalent DO ...