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Informations for hEvaluate.h |
Purpose
To have informations on what the header is capable of doing just follow
this link.
How to use the functions in the expression
In the expressions entered as argument of the Solve function you can
use these operators: +, -, *, /, ^.
Numbers can be entered both as not decimal or decimal and even in
exponential form.
The functions allowed at the moment are:
sine:
double
sin(double
argument)
cosine:
double
cos(double
argument)
tangent:
double tan(double
argument)
Inverse sine:
double asin(double
argument)
Inverse cosine:
double
acos(double
argument)
Inverse tangent:
double
atan(double
argument)
Hyperbolic sine:
double
sinh(double
argument)
Hyperbolic cosine:
double
cosh(double
argument)
Hyperbolic tangent:
double
tanh(double
argument)
Secant:
double sec(double
argument)
Cosecant:
double csc(double
argument)
Cotangent:
double cot(double
argument)
Exponential:
double exp(double
argument)
Natural logarithm:
double
ln(double
argument)
Logarithm in a chosen base:
double
log(double
argument)
Square root:
double sqrt(double
argument)
Root with a chosen index:
double
rt(double
argument)
Absolute value:
int
abs(double
argument)
Sources informations
The actual vesion is the 2.2.
Here you can have informations on how to use the hEvaluate.h header
in your programs and various technical specifications on the several
functions it offers.
How to use the solver
The main function present in hEvaluate is the function Solve:
int
Solve (char
sExpression[], short int
&iErrorPosition,
short int &iErrorType);
| Parameters |
sExpression[] is
the string which contains the expression to be evaluated. The
string must have the terminator at the end. The variable, if a
valid expression, will be replaced by the result.
iErrorPosition
is a variable, passed by address (so modifiable). It will contain
the position of the first eventually found error. If no error is
found, the variable will remain unchanged.
iErrorType
is a variable passed by address which will contain the code to
describe the error found (if found).
-1
-- A general syntax error has been found (ex. "**").
-2
-- The operation 0/0 has been found during the parsing.
-3
-- The operation n/0 (with n belonging to the reals) has been
found during the parsing.
-4
-- A not recognized function has been found.
-5
-- Error computing the function asin(double). The argument must be
comprised between -1 and 1.
-6
-- The same as in -5, but in this case the error is in the
function acos.
-7
-- Error found during the computing of a logarithm. The argument
must be grater than 0.
-8
-- Error found during the computing a a logarithm, the base must
be grater than 0 and different from 1.
-9
-- Found a aquare root of a negative number. The dominion is for
each "not negative" x.
-10
-- Error found during the computing of a root with peer index with
a negative argument. This error is very similar to the previous
one but it's not the same. This refers to the function rt(double
base, double argument) whereas the previous refers to the function
sqrt(double argument). In this way it is even possible to
differentiate between the two cases if needed. |
| Returned value |
The value return is an integer and can
be 0 or 1. If it is 0 then at least one error has been found,
otherwise no error has been found. If the
returned value is 0 then you can use the last two variables to
understand what has gone wrong. If the returned value is 1 the last
two variables have not been modified. |
Complete functions reference
|
int
Solve (char
sExpression[], short int
&iErrorPosition,
short int &iErrorType); |
| Already
expleined above. |
|
int
Evaluate (char
sExpression[],
short int
&iErrorPosition,
short int
&iErrorType); |
| This
function can solve an expression without parenthesis. The
arguments are the same of those used by the Solve function. |
|
int
CheckExpression (char
sExpression[],
short int
&iErrorPosition); |
| The
CheckExpression can check the presence of some not allowed
syntaxes. If an error is found than iErrorPosition will contain
the position of the error in the vector. sExpression is a vector
containing the expression to be checked. |
|
bool
CheckSeparator (char
sExpression[]); |
| The
CheckSaperator function is able to determine whether in the
expression passed as a string, a separator is present. A separator
is the character ",", which is used in some functions to separate
two parameters. This function is used inside the parsing process
to understand if a simplified expression mast be re-inserted
inside its parenthesis (because containing arguments of a function)
or not. |
|
bool
CheckOperator (char
sExpression[]); |
| The
CheckOperator can determine if in the expression passed there is
unless one operator. CheckOperator is able to understand the
difference between a operator and a symbol intended as a sign like
(+2). sExpression is obviously the expression to be checked. |
|
void
ReplaceString (char
sExpression[],
char
sNewString[],
int
iStart,
int iEnd); |
|
ReplaceString can be used to replace the elements present in
sExpression from iStart (comprised) to iEnd (not comprised) with
the elements of the string sNewString. Both sNewString and
sExpression must be zero termiinated. iStart is the first element
which will be substituted. The element in position iEnd wil not be
sobstituted. |
|
void
SortParenthesis (char
sExpression[]); |
|
SortParenthesys fills the parenthesis structure with informations
regarsing the position of open and close parenthesis in the
expression passed with sExpression. |
|
bool
IsNumber (char
sExpression[], int
iSymbolPosition, bool
bConsiderPoint, bool
bConsiderExponential); |
|
IsNumber returns true if the character in position iSymbolPosition
in the vector sExpression is a number. Otherwise the returned
value is false. The value bConsiderPoint must be set to true if
you want the function to consider the point (as decimal separator)
as part of the number. The bConsiderExponential is not yet
foreseen, but is handled by the other functions. |
|
bool
IsLetter (char
sExpression[], int
iSymbolPosition, bool
CheckE); |
|
IsLetter return true if the element in iSymbolPosition of
sExpression is a letter, otherwise the returned value id false.
The CheckE variable must be set to true if you want to handle
exponential numbers. |
|
void
EvaluatePowers (char
sExpression[]); |
|
Evaluates all the powers found in the given expression. No
returned value is present. |
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int
EvaluateMultiplications (char
sExpression[],
short int
&iErrorPosition,
short int
&ErrorType); |
|
Evaluates alla the multiplications and divisions present in
sExpression. If a n/0 or 0/0 is found, then the returned value is
false. In this case iErrorPosition and ErrorType will be used.
iErrorPosition will be the position of the first element belonging
to the error. ErrorType is needed to distinguish the difference
between 0/0 and n/0. If no error is found the returned result is
true. |
|
void
EvaluateAdditions (char
sExpression[]); |
|
Computes all the additions and differences. |
|
int
EvaluateFunctions (char
sExpression[],
short int
&iErrorPosition,
short int
&iErrorType); |
| The
EvaluateFunction evaluates every function in the expression given.
The returned value is true if no error is found, otherwise the
returned value is false. In case it is false, iErrorPosition and
iErrorType will contain the position of the error and the type of
error. For the error code see the table above. |
|
double
FindOperator (char
sExpression[],
int
iSymbolPosition,
char
cLastSymbol,
bool
bFindFirst); |
|
FindOperator can find the operand after or befor the operator.
iSymbolPosition is the position of the operator, last symbol is
the last simbol of the operator (or of the function). bFindFirst
must be set to true if you want the first operator, set to false
if you want the second. The returned value is the operator. |
|
int
FindFunction (char
sExpression[],
int
iStart); |
|
FindFunction can be called to understand if in position iStart
there is a known function. If a function is found then its code
will be returned. |
Download informations
Download the hEvaluate header
(.zip format)
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