Returns integer information describing the computer’s arithmetic.
Synopsis
#include <imsls.h>
long imsls_i_machine (int n)
Required Arguments
int n
(Input)
Index indicating which value is to be returned. It must be between 0
and 12.
Return Value
The requested value is returned. If n is out of range, NaN is returned.
Description
Function imsls_i_machine returns information describing the computer’s arithmetic. This can be used to make programs machine independent.
imsls_i_machine(0) = Number of bits per byte
Assume that integers are represented in M-digit, base-A form as
where σ is the sign and
0 ≤ xk < A
for k = 0, …, M.
Then,
|
n |
Definition |
|
0 |
C, bits per character |
|
1 |
A, the base |
|
2 |
Ms, the number of base-A digits in a short int |
|
3 |
|
|
4 |
M1 the number of base-A digits in a long int |
|
5 |
|
Assume that floating-point numbers are represented in N-digit, base B form as
where σ is the sign and
0 ≤ xk < B
for k = 1, …, N
and Emin ≤ E ≤ Emax. Then
|
n |
Definition |
|
6 |
B, the base |
|
7 |
Nf, the number of base-B digits in float |
|
8 |
|
|
9 |
|
|
10 |
Nd, the number of base-B digits in double |
|
11 |
|
|
12 |
|
the smallest float
exponent
the largest float
exponent
Example
In this example, all the values returned by imsls_i_machine on a 32-bit machine with IEEE (Institute for Electrical and Electronics Engineer) arithmetic are printed.
#include <imsls.h>
#include <stdio.h>
int main() {
int n;
long ans;
for (n = 0; n <= 12; n++) {
ans = imsls_i_machine(n);
printf("imsls_i_machine(%d) = %ld\n", n, ans);
}
}
Output
imsls_i_machine(0) = 8
imsls_i_machine(1) = 2
imsls_i_machine(2) = 15
imsls_i_machine(3) = 32767
imsls_i_machine(4) = 31
imsls_i_machine(5) = 2147483647
imsls_i_machine(6) = 2
imsls_i_machine(7) = 24
imsls_i_machine(8) = -125
imsls_i_machine(9) = 128
imsls_i_machine(10) = 53
imsls_i_machine(11) = -1021
imsls_i_machine(12) = 1024
