FAQ - Revision history

Jrheinlaender: /* Using iMath questions */

2025-09-14T12:11:56Z

Using iMath questions

← Older revision		Revision as of 12:11, 14 September 2025
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	== Using iMath questions ==		== Using iMath questions ==

			'''Q: I have defined a vector <code>v = ({1;2;3;4})</code>. Why can't iMath reduce <code>v[1]</code> to the value 1?'''

			A: iMath interprets <code>v[1]</code> literally. Since <code>v</code> is just a symbol, the index can not be applied. You need to replace <code>v</code> by its definition, e.g. <code>VAL(v[1])</code> or substitute <code>v = VAL(v)</code> in your equation.

	'''Q: How can I reduce a formula to floating point numbers as far as possible? [[VAL]] does not do this'''		'''Q: How can I reduce a formula to floating point numbers as far as possible? [[VAL]] does not do this'''

Jrheinlaender: /* Mathematical background questions */

2025-02-21T20:49:08Z

Mathematical background questions

← Older revision		Revision as of 20:49, 21 February 2025
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	== Mathematical background questions ==		== Mathematical background questions ==

			'''Q: Why doesn't iMath resolve <code>abs(-a) = a</code> or <code>sqrt{x^2} = x</code>?

			A: This is not mathematically safe. You must tell iMath that your variable is positive-valued by using [[POSVARDEF]].

	'''Q: How can I tell iMath that the cubic root of -1 is -1?'''		'''Q: How can I tell iMath that the cubic root of -1 is -1?'''

Jrheinlaender: /* Mysterious errors */

2025-02-21T20:46:32Z

Mysterious errors

← Older revision		Revision as of 20:46, 21 February 2025
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	== Mysterious errors ==		== Mysterious errors ==

			'''Q: Why doesn't substitution work for a variable?

			A: Possibly you have two variables with identical names, but different domains (complex, real-valued, positive) or commutativity in your equation. This may happen if you do not define [[POSVARDEF]], [[REALVARDEF]], [[VECTORDEF]] or [[MATRIXDEF]] before using a variable for the first time.

	'''Q: I get an error message that says <code>syntax error, unexpected '\n'</code> and iMath marks the end of my formula as the place where the error occurs. But I think that the formula is totally in order.		'''Q: I get an error message that says <code>syntax error, unexpected '\n'</code> and iMath marks the end of my formula as the place where the error occurs. But I think that the formula is totally in order.

Jrheinlaender: /* Mysterious errors */

2024-11-08T20:40:29Z

Mysterious errors

← Older revision		Revision as of 20:40, 8 November 2024
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	Another possible reason is that you are creating an equation, but your formula text does not contain an <code>=</code> sign.		Another possible reason is that you are creating an equation, but your formula text does not contain an <code>=</code> sign.

			'''Q: Why do I get the message <code><nowiki>matrix::pow(): don't know how to handle exponent</nowiki></code>?

			A: This may happen if you use normal multiplication to calculate the scalar product of two vectors. This works, but the underlying GiNaC library resolves the product to a matrix with a single element. If you use a power on the result, you get the error. The work-around is to use the <code>scalprod</code> function.

	'''Q: Why do I get a wrong result in the following example?		'''Q: Why do I get a wrong result in the following example?

Jrheinlaender: /* Using iMath questions */

2022-07-24T05:34:52Z

Using iMath questions

← Older revision		Revision as of 05:34, 24 July 2022
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	== Using iMath questions ==		== Using iMath questions ==

			'''Q: How can I reduce a formula to floating point numbers as far as possible? [[VAL]] does not do this'''

			A: iMath preserves mathematical exactness as far as possible. For example, square roots will not be evaluated to floating point numbers. But you can force iMath to approximate exact numbers by using [[SIMPLIFY]] with the <code>eval</code> simplification.

	'''Q: Is it possible to clear only chosen equations?'''		'''Q: Is it possible to clear only chosen equations?'''

Jrheinlaender: /* Mysterious errors */

2018-09-06T18:50:25Z

Mysterious errors

← Older revision		Revision as of 18:50, 6 September 2018
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	'''Q: I get an error message that says "syntax error, unexpected '\n'" and iMath marks the end of my formula as the place where the error occurs. But I think that the formula is totally in order.~~'''~~		'''Q: I get an error message that says <code>syntax error, unexpected '\n'</code> and iMath marks the end of my formula as the place where the error occurs. But I think that the formula is totally in order.

	A: This happens frequently if you work with vectors, but the left-hand side of the equation has not been defined as a vector. In other words, your expression creates a vector, but you are trying to assign it to a normal variable. Use "iFormula - [[Define vector]]" to define your variable to be a vector before using it.		A: This happens frequently if you work with vectors, but the left-hand side of the equation has not been defined as a vector. In other words, your expression creates a vector, but you are trying to assign it to a normal variable. Use "iFormula - [[Define vector]]" to define your variable to be a vector before using it.
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	A: You need to define <code>FUNCTION {{none}, y, x}</code> before function z(). In the example, you have two different versions of <code>y</code>: When defining function z(), it is a normal variable. After that, you define it to be a function, and then use y() to define the value of z(). When you differentiate z(), the left-hand side is a total differential, but since <code>y</code> is a variable here, <code>dy/dx</code> is zero, so only the second part remains. On the right-hand side, the chain rule is applied to <code>sin(y)</code>, since here it is a function.		A: You need to define <code>FUNCTION {{none}, y, x}</code> before function z(). In the example, you have two different versions of <code>y</code>: When defining function z(), it is a normal variable. After that, you define it to be a function, and then use y() to define the value of z(). When you differentiate z(), the left-hand side is a total differential, but since <code>y</code> is a variable here, <code>dy/dx</code> is zero, so only the second part remains. On the right-hand side, the chain rule is applied to <code>sin(y)</code>, since here it is a function.

			'''Q: What does the message <code>Compile error: invalid map<K, T> key</code> mean?

			A: This error occurs when another <code>soffice...</code> process is running in the background. Usually it happens after a fatal error in Office and the termination of iMath. If you get this error message, try to kill all running instances of the <code>soffice...</code> process in the task manager of your operating system. Then run Office again.

	== Obsolete questions ==		== Obsolete questions ==

Jrheinlaender: /* Using iMath questions */

2018-06-08T17:59:37Z

Using iMath questions

← Older revision		Revision as of 17:59, 8 June 2018
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	'''Q: How can I have iMath print the unit %radian?'''		'''Q: How can I have iMath print the unit %radian?'''

	A: Since %radian is defined as 1, this does not happen automatically. But there is a workaround:		A: Since %radian is defined as 1, this does not happen automatically. But there is a workaround (since iMath 2.2.4)

	<code>%%ii [[UNITDEF]] {"radian", %ra = %~~internalradians~~}		<code>%%ii [[UNITDEF]] {"radian", %ra = %unity}

	%%ii [[OPTIONS]] {units={%ra}}		%%ii [[OPTIONS]] {units={%ra}}
	</code>		</code>

	~~Instead of <code>%internalradians</code> you can put any name you like that is not already in use.~~ For <code>"radian"</code> you can put whatever you would like to see printed as the name of this unit.		For <code>"radian"</code> you can put whatever you would like to see printed as the name of this unit.

	With this workaround you will need to be consistent when using the unit <code>%ra</code>. For example, <code>%ra + 1</code> will not evaluate to 2!		With this workaround you will need to be consistent when using the unit <code>%ra</code>. For example, <code>%ra + 1</code> will not evaluate to 2! Also, trigonometric functions will not evaluate their arguments unless you substitute <code>%unity = 1</code>.

	== Formatting of formulas ==		== Formatting of formulas ==

Jrheinlaender: /* Using iMath questions */

2018-06-05T18:46:18Z

Using iMath questions

@@ Line 36: / Line 36: @@
 '''Q: How can I create a variable named &Delta;x?'''
-A: By calling it <code>nospace{%DELTA x}</code>. Note that the space in the middle is required.
+A: By calling it <code>nospace{%DELTA x}</code>. Note that the space in the middle is required. Another way is to simply use a unicode character (put it into your document somewhere and grab it from there to paste into the formula dialog).
 == Formatting of formulas ==

Jrheinlaender: /* User interface questions */

2017-07-20T19:21:30Z

User interface questions

← Older revision		Revision as of 19:21, 20 July 2017
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	A: No, because the "," is also used to separate arguments to commands. But if your locale is set accordingly, iMath will convert the "." to a "," automatically when printing your formulas		A: No, because the "," is also used to separate arguments to commands. But if your locale is set accordingly, iMath will convert the "." to a "," automatically when printing your formulas

	'''Q: Why is the options dialog ~~Extras~~-Options-Writer-iMath blank?'''		'''Q: Why is the options dialog Tools-Options-Writer-iMath blank?'''

	A: This seems to be a bug in Office when updating iMath. You could try completely removing iMath through the extension manager, closing Office, starting it again, and installing iMath again through the extension manager. Unfortunately, even this does not always remove all traces of the old iMath version. Often I had to remove the complete office configuration directory. For example, on Ubuntu, this is located in .config/libreoffice. On Windows, you should look in C:\users\<username>\Application Data\LibreOffice (or OpenOffice).		A: This seems to be a bug in Office when updating iMath. You could try completely removing iMath through the extension manager, closing Office, starting it again, and installing iMath again through the extension manager. Unfortunately, even this does not always remove all traces of the old iMath version. Often I had to remove the complete office configuration directory. For example, on Ubuntu, this is located in .config/libreoffice. On Windows, you should look in C:\users\<username>\Application Data\LibreOffice (or OpenOffice).


	== Different platforms ==		== Different platforms ==

Jrheinlaender at 16:41, 12 July 2017

2017-07-12T16:41:18Z

← Older revision		Revision as of 16:41, 12 July 2017
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	'''Q: Is it possible to clear only chosen equations?'''		'''Q: Is it possible to clear only chosen equations?'''

	A: You can clear equations by label (select it and choose Edit - Clear from the menu), or use this line in a formula <code>%%ii DELETE{#equation_label#}</code>. A list of labels is also possible.		A: You can clear equations by label (select it and choose Edit - [[Clear]] from the menu), or use this line in a formula <code>%%ii [[DELETE]]{@equation_label@}</code>. A list of labels separated by semicolons is also possible.

	'''Q: How do I hide an equation?'''		'''Q: How do I hide an equation?'''

	A: Select the formula and choose iMath->Edit->Hide/show , alternatively put * after EQDEF.		A: Select the formula and choose iMath - Edit - [[Hide/show]], alternatively put * after [[EQDEF]].

	'''Q: How do I include a *.imath file in the document?'''		'''Q: How do I include a something.imath file in the document?'''

	A: Go to ~~File~~-~~>Properties~~-~~>User~~ defined ~~properties->Include file .imath~~, or use this line in iFormula <code>%%ii READFILE {".imath"}</code>. For example, if you have created 1.imath file in some directory, after READFILE the full path must be given. ~~Here are examples of proper lines under Windows and Ubuntu.~~		A: Go to iMath - [[References]] and write your filename in the User-defined references box, or use this line in an iFormula: <code>%%ii [[READFILE]] {"something.imath"}</code>. For example, if you have created 1.imath file in some directory, after [[READFILE]] the full path must be given. See the documentation for [[READFILE]] for details.

	~~Windows: <code>%%ii~~ READFILE ~~{"C:/Document/1~~.~~imath"}</code>~~

	~~Ubuntu: <code>%%ii READFILE {"/home/user/Documents/1.imath"}</code>~~

	'''Q: I have an equation <code>x = 100 m</code>. How do I tell iMath that the value is in meters?'''		'''Q: I have an equation <code>x = 100 m</code>. How do I tell iMath that the value is in meters?'''

	A: In the new iFormula dialog write this <code>x=100 "m"</code> . The "m" tells iMath that the value is in meters. This will only work if you have included the units~~.imath~~ file ~~with File~~-~~>Properties->User defined properties->Include file units~~.~~imath~~		A: In the new iFormula dialog write this <code>x=100 "m"</code> . The "m" tells iMath that the value is in meters. This will only work if you have included the abbreviated SI units definition file in the iMath - [[References]] dialog.

	'''Q: I can't get iMath to work properly with differentials		'''Q: I can't get iMath to work properly with differentials'''

	A: Here are two rules of thumb for working with differentials:		A: Here are two rules of thumb for working with differentials:
	* You should only use the keyword ~~<code>DIFFERENTIAL</code>~~ when it is really necessary. If you want to create a complete differential like <code>df/dx</code>, use <code>DIFFERENTIATE(f,x,1)</code> instead. iMath will automatically separate this into two differential objects <code>df</code> and <code>dx^{-1}</code>, but will mark them as being connected, so that on printing they can be displayed correctly.		* You should only use the keyword [[differential]] when it is really necessary. If you want to create a complete differential like <code>df/dx</code>, use <code>[[DIFFERENTIATE]](f,x,1)</code> instead.
	* If you want iMath to be able to match differential objects, as in <code>d²f = y dx²</code>, then you must specify them as <code>~~DIFFERENTIAL~~(f,2) = y ~~DIFFERENTIAL~~(x, 2)</code>, not as <code>~~DIFFERENTIAL~~(f,2) = y ~~DIFFERENTIAL~~(x)^2</code>.		* If you want iMath to be able to match differential objects, as in <code>d²f = y dx²</code>, then you must specify them as <code>differential(f,2) = y differential(x, 2)</code>, not as <code>differential(f,2) = y differential(x)^2</code>.
			* See the documentation for [[differential]] and [[DIFFERENTIATE]] for details.

	'''Q: It's such a hassle to type <code>differential(x)</code> all the time. Can't this be shorter, like <code>d(x)</code>?'''		'''Q: It's such a hassle to type <code>differential(x)</code> all the time. Can't this be shorter, like <code>d(x)</code>?'''

	A: Please have a look at the question above and try to avoid using <code>differential</code>.		A: Please have a look at the question above and try to avoid using <code>differential</code>.
	~~Just~~ define a short-cut function yourself, e.g.		Otherwise, just define a short-cut function yourself, e.g.

	<code>%%ii FUNCTION {{expand}, d, y_{_y_}}		<code>%%ii FUNCTION {{expand}, d, y_{_y_}}
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	%%ii @3@ FUNCDEF* d(y_{_y_}) = differential(y_{_y_})		%%ii @3@ FUNCDEF* d(y_{_y_}) = differential(y_{_y_})
	</code>		</code>

			'''Q: How can I create a variable named Δx?'''

			A: By calling it <code>nospace{%DELTA x}</code>. Note that the space in the middle is required.

	== Formatting of formulas ==		== Formatting of formulas ==
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	'''Q: Is it possible to hide units after evaluation?'''		'''Q: Is it possible to hide units after evaluation?'''

	A: Yes, in evaluation formula use NUMVAL instead of VAL. In addition, with iMath 2.1.2 there is now an option that suppresses the display of units ~~altogether~~ (on a per-formula or per-document level).		A: Yes, in evaluation formula use [[NUMVAL]] instead of [[VAL]]. In addition, with iMath 2.1.2 there is now an [[OPTIONS\|option]] that suppresses the display of units alltogether (on a per-formula or per-document level).

	== Mathematical background questions ==		== Mathematical background questions ==
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	A: By default, iMath returns the root on the principal branch (which is complex for negative bases). This is a convention of the underlying GiNaC library which iMath uses to do the calculations.		A: By default, iMath returns the root on the principal branch (which is complex for negative bases). This is a convention of the underlying GiNaC library which iMath uses to do the calculations.
	Starting with iMath 2.1.2, there is ~~a global~~ option "Evaluate to real roots" which will give the desired result. Be aware that turning this option on might break older documents because the results of VAL() statements might be different.		Starting with iMath 2.1.2, there is an [[OPTIONS\|option]] "Evaluate to real roots" which will give the desired result. Be aware that turning this option on might break older documents because the results of [[VAL]] statements might be different.

	'''Q: How do I access Euler's number <code>e</code> in an equation?'''		'''Q: How do I access Euler's number <code>e</code> in an equation?'''

	A: There are two ways: Using the <code>exp()</code> function or using the built-in constant <code>%e</code>. In the latter case you probably want to turn on auto-formatting for the equation to get nicer output (without the % sign).		A: There are two ways: Using the <code>exp()</code> function or using the built-in [[constant]] <code>%e</code>. In the latter case you probably want to turn on auto-formatting for the equation to get nicer output (without the <code>%</code> sign).

	== User interface questions ==		== User interface questions ==
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	A: This seems to be a bug in Office when updating iMath. You could try completely removing iMath through the extension manager, closing Office, starting it again, and installing iMath again through the extension manager. Unfortunately, even this does not always remove all traces of the old iMath version. Often I had to remove the complete office configuration directory. For example, on Ubuntu, this is located in .config/libreoffice. On Windows, you should look in C:\users\<username>\Application Data\LibreOffice (or OpenOffice).		A: This seems to be a bug in Office when updating iMath. You could try completely removing iMath through the extension manager, closing Office, starting it again, and installing iMath again through the extension manager. Unfortunately, even this does not always remove all traces of the old iMath version. Often I had to remove the complete office configuration directory. For example, on Ubuntu, this is located in .config/libreoffice. On Windows, you should look in C:\users\<username>\Application Data\LibreOffice (or OpenOffice).



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	'''Q: I get an error message that says "syntax error, unexpected '\n'" and iMath marks the end of my formula as the place where the error occurs. But I think that the formula is totally in order.'''		'''Q: I get an error message that says "syntax error, unexpected '\n'" and iMath marks the end of my formula as the place where the error occurs. But I think that the formula is totally in order.'''

	A: This happens frequently if you work with vectors, but the left-hand side of the equation has not been defined as a vector. In other words, your expression creates a vector, but you are trying to assign it to a normal variable. Use "iFormula - Define vector" to define your variable to be a vector before using it.		A: This happens frequently if you work with vectors, but the left-hand side of the equation has not been defined as a vector. In other words, your expression creates a vector, but you are trying to assign it to a normal variable. Use "iFormula - [[Define vector]]" to define your variable to be a vector before using it.

			Another possible reason is that you are creating an equation, but your formula text does not contain an <code>=</code> sign.

	'''Q: Why do I get a wrong result in the following example?		'''Q: Why do I get a wrong result in the following example?
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	<code>		<code>
	%%ii FUNCTION {{none}, z, y;x}		%%ii FUNCTION {{none}, z, y;x}

	%%ii FUNCTION {{none}, y, x}		%%ii FUNCTION {{none}, y, x}

	%%ii @eq:1@ EQDEF z = sin {y} + x^2		%%ii @eq:1@ EQDEF z = sin {y} + x^2

	%%ii TEXT newline		%%ii TEXT newline

	%%ii @eq:2@ EQDEF DIFFERENTIATE(@eq:1@, x, 1)		%%ii @eq:2@ EQDEF DIFFERENTIATE(@eq:1@, x, 1)
	</code>'''		</code>'''