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7 Intrinsic Procedures

The intrinsic procedures fall into four distinct categories:

• Elemental procedures
  
  These are specified for scalar arguments, but are also applicable to conforming array arguments applying the procedure element by element.

• Inquiry functions
  
  Inquiry functions return properties of principal arguments that do not depend upon their values.

• Transformational functions
  
  These functions usually have array arguments and an array result whose elements depend on many of the elements in the array.

• Nonelemental Subroutines

7.1 Elemental Procedures

7.1.1 Elemental Functions

CEILING(A)
Smallest integer not less than A.

FLOOR(A)
Largest integer not exceeding A.

MODULO(A,P)
A modulo P for A and P both real or both integer.

ACHAR(I)
Character in position I of ASCII collating sequence.

ADJUSTL(STRING)
Adjust left, change leading blanks into trailing blanks.

ADJUSTR(STRING)
Adjust right, change trailing blanks into leading blanks.

IACHAR(C)
Position of character C in ASCII collating sequence.

INDEX(STRING,SUBSTRING[,BACK])
Starting position of SUBSTRING within STRING. If more than one SUBSTRING than position of first (or last if BACK true) is returned.

LEN_TRIM(STRING)
Length of STRING without trailing blanks.

SCAN(STRING,SET[,BACK])
Index of left-most (right-most if BACK true) character nof string that belongs to SET; zero if none belong.

VERIFY(STRING,SET[,BACK])
The position of left-most (or right-most if BACK true) character of STRING that is not in SET. Zero if each character of STRING appears in SET.

BTEST(I,POS)
True if bit POS of integer I has value 1.

IAND(I,J)
Logical AND on all corresponding bits of I and J.

IBCLR(I,POS)
Bit POS of I cleared to zero.

IBITS(I,POS,LEN)
Extract sequence of LEN bits of I starting from bit POS.

IBSET(I,POS)
Bit POS of I set to 1.

IEOR(I,J)
Logical exclusive OR on all corresponding bits of I and J.

IOR(I,J)
Logical inclusive OR on all corresponding bits of I and J.

ISHFT(I,SHIFT)
Value of I with bits shifted SHIFT places to left (right if negative) and zeros shifted in from other end.

ISHFTC(I,SHIFT[,SIZE])
Value of I with circular shift of SIZE right-most bits SHIFT places to the left (right if negative).

NOT(I)
Logical complement of all bits of I.

SELECTED_INT_KIND(R)
Kind of type parameter for specified exponent range. -1 returned if no such kind is available.

SELECTED_REAL_KIND(P,R)
Kind of type parameter for specified precision and exponent range. -1 returned is precision is unavailable, -2 if range is unavailable and -3 if neither are available.

EXPONENT(X)
Exponent part of the model for X.

FRACTION(X)
Fractional part of the model for X.

NEAREST(X,S)
Nearest different machine number in the direction given by the sign of S

RRSPACING(X)
Reciprocal of relative spacing of the model numbers near X.

SCALE(X I)
X2I (real)

SET_EXPONENT(X,I)
Real whose sign and fractional part are those of X, and whose exponent part is I.

SPACING(X)
Absolute spacing of model numbers near X.

LOGICAL(L[,KIND])
Converts between kinds of logical numbers.

7.1.2 Elemental Subroutine

CALL MVBITS(FROM,FROMPOS,LEN,TO,TOPOS)
Copy LEN bits of FROM starting at position FROMPOS to TO, starting at position TOPOS.

7.2 Inquiry Functions

ASSOCIATED(POINTER[,TARGET])
True if pointer associated with a target. If target present, then true only if associated with specified target.

BIT_SIZE(I)
Maximum number of bits that may be held in an integer.

KIND(X)
Kind type parameter for X.

PRESENT(A)
True if optional argument A is present.

DIGITS(X)
Number of significant digits in the model for X.

EPSILON(X)
Number that is almost negligible compared with 1 in the for numbers like X.

HUGE(X)
Largest number in the model for numbers like X.

MAXEXPONENT(X)
Maximum exponent in the model for numbers like X.

MINEXPONENT(X)
Minimum exponent in the model for numbers like X.

PRECISION(X)
Decimal precision in the model for X.

RADIX(X)
Base of the model for numbers like X.

RANGE(X)
Decimal exponent range in the model that includes integer, real and complex X.

TINY(X)
Smallest positive number in the model for numbers like X.

7.3 Transformational Functions

REPEAT(STRING,NCOPIES)
Concatenates NCOPIES of STRING.

TRANSFER(SOURCE,MOLD[,SIZE])
Same physical representation as SOURCE, but of type MOLD.

TRIM(STRING)
Removes trailing blanks form STRING.

7.4 Non Elemental Intrinsic Subroutines:

CALL DATE_AND_TIME([DATE][,TIME][,ZONE][VALUES])
Real-time clock reading date and time.

RANDOM_NUMBER(HARVEST)
Random numbers in range .

RANDOM_SEED([SIZE][,PUT][,GET])
Initialize or restart random number generator.

SYSTEM_CLOCK([COUNT][,COUNT_RATE][COUNT_MAX])
Integer data from real-time clock.

7.5 Array Intrinsic Procedures

ALL(MASK[,DIM])
True if all elements true

ANY(MASK[,DIM])
True if any element true

COUNT(MASK[,DIM])
Number of true elements

MAXVAL(ARRAY[,DIM][,MASK])
Maximum element value

MINVAL(ARRAY[,DIM][,MASK])
Minimum element value

PRODUCT(ARRAY[,DIM][,MASK])
Product of array elements

SUM(ARRAY[,DIM][,MASK])
Sum of array element

Inquiry

ALLOCATED(ARRAY)
True if array allocated

LBOUND(ARRAY[,DIM])
Lower bounds of array

SHAPE(SOURCE)
Shape of array (or scalar)

SIZE(ARRAY[,DIM])
Size of array

UBOUND(ARRAY[,DIM])
Upper bounds of array

MERGE(TSOURCE,FSOURCE,MASK)
Merge arrays subject to mask

PACK(ARRAY,MASK[,VECTOR])
Pack elements into vector subject to mask

SPREAD(SOURCE,DIM,NCOPIES)
Construct an array by duplicating an array section

UNPACK(VECTOR,MASK,FIELD)
Unpack elements of vector subject to mask

RESHAPE(SOURCE,SHAPE[,PAD][,ORDER])
Reshape array

MAXLOC(ARRAY[,MASK])
Location of maximum element

MINLOC(ARRAY[,MASK])
Location of minimum element

CSHIFT(ARRAY,SHIFT[,DIM])
Perform circular shift

EOSHIFT(ARRAY,SHIFT[,BOUNDARY][,DIM])
Perform end-off shift

TRANSPOSE(MATRIX)
Transpose matrix

DOT_PRODUCT(VECTOR_A,VECTOR_B)
Compute dot product

MATMUL(MATRIX_A,MATRIX_B)
Matrix multiplication

7.6 Exercises

1. Look at the programs char_int.f90, model.f90, mod_int.f90 and convert.f90 and run them.
   
   Notice how these programs use instrinsic functions for certain purposes.