Improve eye func test and doc.

Author: zoziha

doc/specs/stdlib_linalg.md

@@ -121,19 +121,13 @@ This is an `intent(in)` argument.
 `dim2`: Shall be a scalar of default type `integer`.
 This is an `intent(in)` and `optional` argument. 
 
-#### Note
-
-Because of `huge(integer :: i) = 2147483647`, the dimensional maximum length of array created by the `eye` function is `2147483647`. 
-
 ### Return value
 
-Return the identity matrix, i.e. a square matrix with ones on the main diagonal and zeros elsewhere. The return value is of type `integer`.
+Return the identity matrix, i.e. a matrix with ones on the main diagonal and zeros elsewhere. The return value is of type `integer`.
 
 #### Warning
 
-If the array that receives the return value of the `eye` function is of `real/complex` type, conversion from `integer` type to `real/complex` type will occur.  
-
-Just as `Fortran` is a strongly typed statically compiled language, be careful with the following statements:
+Since the result of `eye` is of `integer` type, one should be careful about using it in arithmetic expressions. For example:
 ```fortran
 real :: A(:,:)
 !> Be careful

src/tests/linalg/test_linalg.f90

@@ -85,15 +85,15 @@ subroutine test_eye
                msg="all(eye(3,3) == diag([(1,i=1,3)])) failed.",warn=warn)
 
     rye = eye(3,4)
-    call check(sum(rye(:,1:3) - diag([(1.0_sp,i=1,3)])) < sptol, &
-               msg="sum(rye(:,1:3) - diag([(1.0_sp,i=1,3)])) < sptol", warn=warn)
+    call check(sum(abs(rye(:,1:3) - diag([(1.0_sp,i=1,3)]))) < sptol, &
+          msg="sum(abs(rye(:,1:3) - diag([(1.0_sp,i=1,3)]))) < sptol failed", warn=warn)
 
     call check(all(eye(5) == diag([(1,i=1,5)])), &
           msg="all(eye(5) == diag([(1,i=1,5)] failed.",warn=warn)
 
     rye = eye(6)
-    call check(sum(rye - diag([(1.0_sp,i=1,6)])) < sptol, &
-          msg="sum(rye - diag([(1.0_sp,i=1,6)])) < sptol failed.",warn=warn)
+    call check(sum(abs(rye - diag([(1.0_sp,i=1,6)]))) < sptol, &
+          msg="sum(abs(rye - diag([(1.0_sp,i=1,6)]))) < sptol failed.",warn=warn)
 
     cye = eye(7)
     call check(abs(trace(cye) - cmplx(7.0_sp,0.0_sp,kind=sp)) < sptol, &