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\layout Title

Rascal
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the Advanced Scientific CALculator
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Userguide
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\layout Author

Sebastian Ritterbusch
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Introduction
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Rascal is based on an extremely modular approach; depending on the user's
 needs, various powerful modules can be compiled into the system.
 Thus Rascal can be a light-weight tool as well as a very powerful computational
 system.
 This user documentation is created during compilation and describes the
 included features.
 
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Basic Usage 
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Invoking the program leads to a prompt where you can enter expressions.
 The expressions or definitions are being evaluated as soon you press return.
 A semicolon at the end suppresses any output.
 As an example: 
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>5+2
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7
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>5+2;
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>
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Variables are also supported, where the names are case-sensitive alphabetic
 letters and may be followed by numbers.
 An assignment is done using the equal sign:
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>MyVariable2=7; 
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>MyVariable2*MyVariable2
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49
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>
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Undefined variables are always assumed to be integer zeros.
 
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The user can also define functions of one variable (
\begin_inset Formula \( n \)
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-ary functions can be implemented using vectors or matrices as arguments).
 The names follow the same rules as the names of variables:
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>MyNiceFunction17(x)=x*x+5*x;
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>MyNiceFunction17(2)
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14
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>EvalAt12(F)=F(12);
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>EvalAt12(sqr)
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 144 
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The semicolon at the end of the definition is mandatory and the calling-method
 is 
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call by variable
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, similar to parametric 
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#define
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s in C++ with the difference that changes in the operand-variables are not
 forwarded to the original variable.
 Of course functions can be nested and invoked with any data-type.
 If the data-type does not support a certain operation, an error occurs.
 The last example shows how functions can be used as variables, here the
 function value of 
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square
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 at 12 was computed.
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Conditional expressions can be realized using the C-style 
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?:
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-operator:
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>5==3?2.3:17
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17
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>abs(x)=x>0?x:-x;
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>abs(-18)
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18
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>abs(12)
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12    
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>
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If the condition before the questionmark is true, the first expression is
 returned, else the second.
 In contrast to C the result-types of the two alternatives here can be different
, also both alternatives are computed before the decision takes place, thus
 recursions are not possible.
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You can exit Rascal by entering 
\begin_inset Quotes eld
\end_inset 

quit
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 followed by a return.
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If Rascal was compiled using the 
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libreadline
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, then you may use the cursor-keys to flip back to commands and results
 from before, as well as benefit of command completition using the 
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\end_inset 

tab
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\end_inset 

-key.
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Furthermore the different modules predefine functions, which are documented
 in the following sections.
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\begin_inset Include \input{value.tex}

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Questions?
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Send questions, ideas, hints and congratulations to 
\emph on 
rascal@ritterbusch.de.
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Licence
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This program is free software; you can redistribute it and/or modify it
 under the terms of the GNU General Public License as published by the Free
 Software Foundation; either version 2 of the License, or (at your option)
 any later version.
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This program is distributed in the hope that it will be useful, but WITHOUT
 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 FOR A PARTICULAR PURPOSE.
 See the GNU General Public License for more details.
 
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You should have received a copy of the GNU General Public License along
 with this program; if not, write to the Free Software Foundation, Inc.,
 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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