What do 1 INF00 -1 IND00 and -1 IND mean

Question

I m messing around with some C code using floats  and I m getting 1  INF00  -1  IND00 and -1  IND when I try to print floats in the screen  What does those values mean   I believe that 1  INF00 means positive infinity  but what about -1  IND00 and -1  IND  I also saw sometimes this value  1  NaN which is Not a Number  but what causes those strange values and how can those help me with debugging   I m using MinGW which I believe uses IEEE 754 representation for float point numbers   Can someone list all those invalid values and what they mean

User · Answer

For those of you in a  NET environment the following can be a handy way to filter non-numbers out  this example is in VB NET  but it s probably similar in C     If Double IsNaN MyVariableName  Then     MyVariableName   0   Or whatever you want to do here to  correct  the situation End If   If you try to use a variable that has a NaN value you will get the following error      Value was either too large or too small for a Decimal

User · Answer

From IEEE floating-point exceptions in C         This page will answer the following questions          My program just printed out 1  IND or 1  INF  on Windows  or nan or inf  on Linux   What happened    How can I tell if a number is really a number and not a NaN or an infinity    How can I find out more details at runtime about kinds of NaNs and infinities    Do you have any sample code to show how this works    Where can I learn more          These questions have to do with floating point exceptions  If you get some strange non-numeric output where you re expecting a number  you ve either exceeded the finite limits of floating point arithmetic or you ve asked for some result that is undefined  To keep things simple  I ll stick to working with the double floating point type  Similar remarks hold for float types       Debugging 1  IND  1  INF  nan  and inf      If your operation would generate a larger positive number than could be stored in a double  the operation will return 1  INF on Windows or inf on Linux  Similarly your code will return -1  INF or -inf if the result would be a negative number too large to store in a double  Dividing a positive number by zero produces a positive infinity and dividing a negative number by zero produces a negative infinity  Example code at the end of this page will demonstrate some operations that produce infinities       Some operations don t make mathematical sense  such as taking the square root of a negative number   Yes  this operation makes sense in the context of complex numbers  but a double represents a real number and so there is no double to represent the result   The same is true for logarithms of negative numbers  Both sqrt -1 0  and log -1 0  would return a NaN  the generic term for a  number  that is  not a number   Windows displays a NaN as  -1  IND   IND  for  indeterminate   while Linux displays nan  Other operations that would return a NaN include 0 0  0 8  and 8 8  See the sample code below for examples        In short  if you get 1  INF or inf  look for overflow or division by zero  If you get 1  IND or nan  look for illegal operations  Maybe you simply have a bug  If it s more subtle and you have something that is difficult to compute  see  Avoiding Overflow  Underflow  and Loss of Precision  That article gives tricks for computing results that have intermediate steps overflow if computed directly

User · Answer

From IEEE floating-point exceptions in C         This page will answer the following questions          My program just printed out 1  IND or 1  INF  on Windows  or nan or inf  on Linux   What happened    How can I tell if a number is really a number and not a NaN or an infinity    How can I find out more details at runtime about kinds of NaNs and infinities    Do you have any sample code to show how this works    Where can I learn more          These questions have to do with floating point exceptions  If you get some strange non-numeric output where you re expecting a number  you ve either exceeded the finite limits of floating point arithmetic or you ve asked for some result that is undefined  To keep things simple  I ll stick to working with the double floating point type  Similar remarks hold for float types       Debugging 1  IND  1  INF  nan  and inf      If your operation would generate a larger positive number than could be stored in a double  the operation will return 1  INF on Windows or inf on Linux  Similarly your code will return -1  INF or -inf if the result would be a negative number too large to store in a double  Dividing a positive number by zero produces a positive infinity and dividing a negative number by zero produces a negative infinity  Example code at the end of this page will demonstrate some operations that produce infinities       Some operations don t make mathematical sense  such as taking the square root of a negative number   Yes  this operation makes sense in the context of complex numbers  but a double represents a real number and so there is no double to represent the result   The same is true for logarithms of negative numbers  Both sqrt -1 0  and log -1 0  would return a NaN  the generic term for a  number  that is  not a number   Windows displays a NaN as  -1  IND   IND  for  indeterminate   while Linux displays nan  Other operations that would return a NaN include 0 0  0 8  and 8 8  See the sample code below for examples        In short  if you get 1  INF or inf  look for overflow or division by zero  If you get 1  IND or nan  look for illegal operations  Maybe you simply have a bug  If it s more subtle and you have something that is difficult to compute  see  Avoiding Overflow  Underflow  and Loss of Precision  That article gives tricks for computing results that have intermediate steps overflow if computed directly

User · Answer

Your question  what are they  is already answered above   As far as debugging  your second question  though  and in developing libraries where you want to check for special input values  you may find the following functions useful in Windows C      isnan     isfinite    and  fpclass    On Linux Unix you should find isnan    isfinite    isnormal    isinf    fpclassify   useful  and you may need to link with libm by using the compiler flag -lm

User · Answer

From IEEE floating-point exceptions in C         This page will answer the following questions          My program just printed out 1  IND or 1  INF  on Windows  or nan or inf  on Linux   What happened    How can I tell if a number is really a number and not a NaN or an infinity    How can I find out more details at runtime about kinds of NaNs and infinities    Do you have any sample code to show how this works    Where can I learn more          These questions have to do with floating point exceptions  If you get some strange non-numeric output where you re expecting a number  you ve either exceeded the finite limits of floating point arithmetic or you ve asked for some result that is undefined  To keep things simple  I ll stick to working with the double floating point type  Similar remarks hold for float types       Debugging 1  IND  1  INF  nan  and inf      If your operation would generate a larger positive number than could be stored in a double  the operation will return 1  INF on Windows or inf on Linux  Similarly your code will return -1  INF or -inf if the result would be a negative number too large to store in a double  Dividing a positive number by zero produces a positive infinity and dividing a negative number by zero produces a negative infinity  Example code at the end of this page will demonstrate some operations that produce infinities       Some operations don t make mathematical sense  such as taking the square root of a negative number   Yes  this operation makes sense in the context of complex numbers  but a double represents a real number and so there is no double to represent the result   The same is true for logarithms of negative numbers  Both sqrt -1 0  and log -1 0  would return a NaN  the generic term for a  number  that is  not a number   Windows displays a NaN as  -1  IND   IND  for  indeterminate   while Linux displays nan  Other operations that would return a NaN include 0 0  0 8  and 8 8  See the sample code below for examples        In short  if you get 1  INF or inf  look for overflow or division by zero  If you get 1  IND or nan  look for illegal operations  Maybe you simply have a bug  If it s more subtle and you have something that is difficult to compute  see  Avoiding Overflow  Underflow  and Loss of Precision  That article gives tricks for computing results that have intermediate steps overflow if computed directly

User · Answer

For anyone wondering about the difference between -1  IND00 and -1  IND  which the question specifically asked  and none of the answers address    -1  IND00  This specifically means a non-zero number divided by zero  e g  3 14   0  source   -1  IND  a synonym for NaN   This means one of four things  see wiki from source    1  sqrt or log of a negative number  2  operations where both variables are 0 or infinity  e g  0   0  3  operations where at least one variable is already NaN  e g  NaN   5  4  out of range trig  e g  arcsin 2

User · Answer

From IEEE floating-point exceptions in C         This page will answer the following questions          My program just printed out 1  IND or 1  INF  on Windows  or nan or inf  on Linux   What happened    How can I tell if a number is really a number and not a NaN or an infinity    How can I find out more details at runtime about kinds of NaNs and infinities    Do you have any sample code to show how this works    Where can I learn more          These questions have to do with floating point exceptions  If you get some strange non-numeric output where you re expecting a number  you ve either exceeded the finite limits of floating point arithmetic or you ve asked for some result that is undefined  To keep things simple  I ll stick to working with the double floating point type  Similar remarks hold for float types       Debugging 1  IND  1  INF  nan  and inf      If your operation would generate a larger positive number than could be stored in a double  the operation will return 1  INF on Windows or inf on Linux  Similarly your code will return -1  INF or -inf if the result would be a negative number too large to store in a double  Dividing a positive number by zero produces a positive infinity and dividing a negative number by zero produces a negative infinity  Example code at the end of this page will demonstrate some operations that produce infinities       Some operations don t make mathematical sense  such as taking the square root of a negative number   Yes  this operation makes sense in the context of complex numbers  but a double represents a real number and so there is no double to represent the result   The same is true for logarithms of negative numbers  Both sqrt -1 0  and log -1 0  would return a NaN  the generic term for a  number  that is  not a number   Windows displays a NaN as  -1  IND   IND  for  indeterminate   while Linux displays nan  Other operations that would return a NaN include 0 0  0 8  and 8 8  See the sample code below for examples        In short  if you get 1  INF or inf  look for overflow or division by zero  If you get 1  IND or nan  look for illegal operations  Maybe you simply have a bug  If it s more subtle and you have something that is difficult to compute  see  Avoiding Overflow  Underflow  and Loss of Precision  That article gives tricks for computing results that have intermediate steps overflow if computed directly

User · Answer

For anyone wondering about the difference between -1  IND00 and -1  IND  which the question specifically asked  and none of the answers address    -1  IND00  This specifically means a non-zero number divided by zero  e g  3 14   0  source   -1  IND  a synonym for NaN   This means one of four things  see wiki from source    1  sqrt or log of a negative number  2  operations where both variables are 0 or infinity  e g  0   0  3  operations where at least one variable is already NaN  e g  NaN   5  4  out of range trig  e g  arcsin 2

User · Answer

For those of you in a  NET environment the following can be a handy way to filter non-numbers out  this example is in VB NET  but it s probably similar in C     If Double IsNaN MyVariableName  Then     MyVariableName   0   Or whatever you want to do here to  correct  the situation End If   If you try to use a variable that has a NaN value you will get the following error      Value was either too large or too small for a Decimal

User · Answer

Your question  what are they  is already answered above   As far as debugging  your second question  though  and in developing libraries where you want to check for special input values  you may find the following functions useful in Windows C      isnan     isfinite    and  fpclass    On Linux Unix you should find isnan    isfinite    isnormal    isinf    fpclassify   useful  and you may need to link with libm by using the compiler flag -lm

[c++] What do 1.#INF00, -1.#IND00 and -1.#IND mean?

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